I think of it as a safety net.

If Microsoft ever damages the reputation of Windows too much, ReactOS can act as a drop-in replacement for many things with relatively little investment compared to migrating to an OS on another kernel. Even if they're not currently a threat Windows, they have done enough of the groundwork that some extra funding and support could make them a serious competitor should the need ever arise.

Plus, it's just cool.

> relatively little investment compared to migrating to an OS on another kernel

One of the more beautiful aspects of Windows is you actually rarely interact with the kernel at all. That portion of the OS could (and in practice often is) switched out and replaced without the user-facing portions being aware.

If you look at the list of NT system calls [0] you can see how frequently they've changed. The only programs that can safely talk to the kernel are core OS components, which in turn provide a user-facing stable ABI through the use of DLLs.

The fact Wine is running on a separate kernel is essentially 100% transparent to all but a handful of programs that intentionally poke the kernel, either for undocumented functionality or to e.g. detect tampering.

This is why IMO for running application software, Wine will always be superior. Linux is a really good kernel for almost everything, and with io_uring the last big deficit (async i/o) may be fixed.

ReactOS's remaining advantages are driver support for Win2k, and the whole explorer shell and start menu environment. If someone really wanted to, I bet you could run ReactOS's shell on top of Wine, fullscreened on Linux...

[0] https://j00ru.vexillium.org/syscalls/nt/32/

EDIT:

A thought I had after finishing this. Another benefit of ReactOS's architecture vs Wine is you could, in principle, directly copy at least some system-level DLLs/software from Windows (2000/XP) and get something akin to Windows 2003/XP running on a modern and up-to-date kernel, possibility with much newer hardware support.

I doubt the ReactOS devs themselves would want to get that close to even just binary blobs from Microsoft, but if it gets far enough along, I could see users scrapping together systems like this, maybe for retro games or something.

Why does it need an endgame? As long as it has enough interest to keep it going, then they should make whatever they like.

Not everything has to be #1 to be sustainable, interesting and/or worthwhile.

Preservation. Think a library or museum archiving a piece of human culture. Not just the OS itself but the programs that run on the OS. If ReactOS succeeds you'd be able to run those Win95/98/XP era programs literally forever (think 100 years from now) as long as ReactOS is kept up to date and compiled on new processor architectures. Sure you can target running the real original OS as well but this requires a virtual machine and doesn't always work right, since drivers have to be written for the legacy OS to support the VM virtual hardware in some cases.

When Linux the kernel will eventually be completely absorbed into systemd, and the Mac will turn into one giant Touch Bar, there will remain only two contenders for the reasoned user: Windows and ReactOS. (Unless Apple buys Microsoft by then, that is.)

Windows will turn into one big fullscreen candy crush. React OS IS THE end game.

How much of the windows churn over the past decade has been widely accepted as good by the users?

They only really need to get to a XP64/win7 level of win32 capability with the ability to run a recent graphics stack and they will win. They have been getting closer to the "just" works bit every year. At some point I suspect their market share will start to rise enough that application vendors start assuring their programs work properly.

At which point they could have a larger market impact than macos has had for the past 30 years.

I have been as skeptical as the parent post. You make a good point though. Getting to Windows 7 at any point this decade will give them a real shot at increasing user base. I assume most people would be happy on Windows 7 as on Windows 10 outside of becoming comfortable on Windows 10 over the past 5 yrs

What makes you think being more popular, as popular, or even a fraction as popular as Windows (which is used on billions of devices) is a goal?

I can think of some niche use-cases. For example, my mother owns a perfectly functional printer and spent quite a lot of money on ink cartridges, only to have the manufacturer refuse to provide drivers beyond Windows 7 (and never bothered supporting anything but Windows). React OS could allow her to continue using this otherwise functioning printer until she runs out of ink and cannot buy any more cartridges.

There are probably tons of other weird devices out there that are beyond their official EOL and require some previous version of Windows to continue to be used. There is also a lot of software that people depend on but which is either EOL or the original software vendor is defunct, and React OS can provide a compatible environment to run that software on regardless of what Microsoft chooses to do with more recent versions of Windows. It may seem crazy and there are probably a variety of security issues with running unsupported software, but for some people the risk will be worth it.

I've noticed a couple things over the last half decade:

- Windows has gone very stagnant IMO. Sure they might have a bunch of new apis for 8/10, but... are there killer apps for them?

- Windows is no longer in growth phase. COVID computer demand surge is a temporary measure, and will probably be followed with a long shallow valley

- ARM is coming on the desktop, and it's going to destroy Windows backwards compatibility. That creates a tentpole point for ReactOS to target for compatibility, and likely something that, like Dosbox, microsoft would de facto embrace to alleviate itself of pressures of backwards compatibility

So I think ReactOS could settle into the "backwards compatibility VM" that windows could (should) actively support so they can move onto a new processor architecture.

I think there's a huge argument for a "controlled" Windows-compatible OS.

There are a lot of workflows dependent on software and devices that never had a proper update to support past Windows XP 32-bit.

Even if you use license-downgrade rights, it's going to get harder and harder to find the actual bits you need to keep such systems alive.

ReactOS could potentially provide that steady-state-- a perpetually available Windows XP, which is also recent enough that you could see new drivers added and software ported so you could still boot it on a commodity PC.

I think with Windows 10 being the last version of Windows, ReactOS will eventually catch up.

Also: If Windows starts getting real ugly with forced telemetry, cloud service integration, and deprecation of Win32 apps, ReactOS can provide a way to continue using "Windows" in a productive manner without the negative side effects of ad-surveillance and forcing you to upgrade your PC every X interval like a phone.

Hopefully Microsoft doesn't make any other app become basically unremoveable like Internet Explorer and Cortana.

> I think with Windows 10 being the last version of Windows, ReactOS will eventually catch up.

Windows 10 certainly isn't the "last version" of Windows in the sense you are thinking.

Even if there is no new version number, they could likely just drop that and call it "Windows" from now on. I haven't heard of any plans to discontinue desktop development.

It will just be constantly updated, as we are seeing it now.

Like the major UI revamp in the works codenamed 'Sun Valley', due later in 2021.

https://www.windowscentral.com/windows-10-sun-valley-ui-octo...

It might be a good open source desktop environment option for the future. Something like what Haiku tries to be.

You may have not realized but Windows has been in maintenance mode for a while, since v10. Aka the last Windows.

Windows has not been in maintenance mode and Windows 10 is not the last version of Windows: https://www.theverge.com/2021/1/4/22212817/microsoft-windows...

The amount of investment is down substantially, not even including the decimation of QA.

You'll have to do better than a new color scheme and fixing the dialogs they broke since Win7.

Now Windows terminal is something to talk about, but the number of devoted team members appears to be under 5.

is this why windows 10 continues to get new features?

For those completely out of the Windows-loop : what are those new features?

I do know about WSL, which you could consider an anti-feature in a way.

ReactOS should be pretty interesting for any Windows shop. If you have some in house app and you can run it in reactos, you can stop paying licences.

How dare you. It is not AS3.

...what does ReactOS have to do with ActionScript 3?