The latest version of MacOS supports computers back to 2012.
But while the Mac is not a huge percentage of Apple’s revenue, by itself, it makes enough money to be a Fortune 100 company.
The number of applications installed doesn't matter. iOS will purge apps if they are running in the background and take up too much CPU or memory. You're not going to have > 10 apps running in the background. More than likely, you won't have any third party apps using CPU time in the background besides playing music or VOIP.
EDIT:
Just realized that you may be referring to macOS. In that case, that would be RAM and/or disk dependent (SSD vs spinning hard drives).
Chrome OS itself isn't going anywhere.
As developers we understand the value of the ecosystem and we want to invest in products that last longer that one or two years.
Also I own Apple and Thinkpad laptops that are between 1 and 7 years old and all of them are still working fine. Laptops last longer than smartphones so you want to ensure the platform will be supported for the next 10 years.
Can you honestly say that Google will support Chrome OS for the next 10 years? Personally I doubt it.
I work for Chrome OS, opinions are my own.
I think yes it will be supported because Google is trying very hard to diversify its revenue streams and Chrome OS actually makes money and is still growing quickly.
Note that Chrome OS is an entirely separate PA (product area) from Hardware.
Regardless of whether or not Chrome OS is here to stay—I very much think it is, personally—Google closing their hardware division doesn't tell us much about Chrome OS's future. Only a tiny fraction of Chrome OS hardware comes from Google itself.
I couldn't disagree more. When I buy a laptop, I want to know that all the time I invest in learning that ecosystem and customizing won't be wasted time. Or any other hardware. Especially if I have to buy apps for it. I want to know that when I get the next piece of hardware, it will support all the software I already know and love (and paid for!)
I'm reluctant to buy into an ecosystem that might be on the decline, because it means a higher chance of that stuff not working anymore.
I kind of speak from both sides of this, I had some audio hardware I bought but one day they went radio silent (404 site so presumably belly up), so future support was dead along with all their support drivers. Another was an internship I did at a hardware company where there was just maintenance patches being applied to the product, and it was depressing.