This isn't a fundamental change to ChromeOS -- it's just a compatibility library. Maybe they should go all out and port WINE to ChromeOS next.
Personally, permissions are the one area of Android that I'm not happy with, because permissions being all-or-nothing means that apps can twist my arm to give them access to things I'd rather they not have access to (e.g. contacts). Seeing ChromeOS adopt this security model would make it less appealing to me rather than more appealing, because it encourages apps to demand access to more data than they need.
On Android, this is not the case; if you use the Facebook or LinkedIn apps, you will be forced to give up access to your contacts (unless you root your device). The reasons for this are twofold. First, Android permissions are all-or-nothing, which means that apps have to over-approximate their required permissions. Second, because granting access is so easy (no UX hurdle to speak of), there's really no downside to doing so (which is to say, conversion rates will not decrease substantially).
The issue of how the device gets access to the data (e.g. whether contacts are cached locally or are purely remote) is really not the issue. You could easily implement the Android API with no local caching of data, and aside from the performance hit the behavior would be identical.
I could certainly imagine a version of ChromeOS which supports Android apps without the Android permission model, essentially by returning empty data sets whenever the app asks. This would be compatible with ChromeOS's current security policies, and would protect user privacy. But it would be so easy for Google to break that line in order to promote "better UX" for apps in the style of Android, that I can't honestly convince myself that they'll never go down that road. And that's why I can't be entirely comfortable with believing the ChromeOS security model will remain intact.
I think there are few things remaining for Android to replace Windows (in no particular order):
1. UX - what you already said.
2. Cheap and universal docks for even cheapest devices. Alternatively cheap wireless display technology (without lags), something more than ChromeCast - again even for cheapest devices.
What can be used for this? Bluetooth (sound and input) and/or USB-OTG (with charging of device).
3. Android needs to be selfhosting - you can't rely on Windows or traditional desktop linux if you want to replace them. There is toybox and Aborginal Linux project from Rob Landley on http://landley.net/ Recent commits advancing in the goal of building Linux kernel with clang will come in handy too.
I think that all of these will eventually come, but ask myself is this what Google really wants now.
ChromeOS seems more in line with Google business model.
They are using NaCl to bring Android apps to ChromeOS, so probably it could enable Android apps for Windows. But that would undermine Android as replacement of Windows just like Wine for Desktop Linux.
It's not supported by Google (no Play services AFAIK) but most applications that are installable from a 3rd party app store should run (they're JVM apps after all).
But why would you want to run Android on your PC? What advantages does it offer over Windows for the average user?
Interesting point... I recently helped an elderly man (who has very poor reading skills and has never used a computer without help) - buy, set-up, and use his first computer. What did I choose for him?
A cheap Android tablet with a keyboard case. The idea behind this decision was that most people (in a low-income area) that he'd ask for help would already know how to work an Android tablet because they probably have a phone or tablet already. If not, he knows the basics, and it's much more simple than a PC but almost fully-capable with his needs (Facebook, PayPal, YouTube). I also locked it down so that he could get help with his financial data without giving anybody the actual password to his bank accounts (as he was doing before).
I suspect that putting Android apps on ChromeOS isn't that hard now, given all the work that's gone into Native Client and that even if the beta of the Android Runtime being used wasn't announced until I/O this year, the end goal of doing this has probably been part of the motivation behind Native Client for some time.
In fact, the fact that its in Beta and they are starting to publicly expose it with high-visibility apps probably means that its mostly done. And its potentially a much bigger win than expanding Android to low-end PCs, since there's no reason when its completely ready to leave Beta it has to be limited to ChromeOS -- a Native Client based runtime for apps should be usable on Chrome desktop as well, which suddenly means "Android" apps can be used on Android (naturally), on ChromeOS, and on MacOS/Windows desktop.
This way when your hardware cycle is up. Hmmm $300 machine runs chrome and all those cool apps I use on my mobile but for my "desktop".
The goal is to erase the idea of desktop all together for the most part.
Personally I hope that Android with or without Google will replace Windows.
And I say this as someone who really likes the Pixel otherwise.
Have you tried running at 2560 x 1700 on the most up-to-date version of ChromeOS? Some of the issues you had may have been fixed in more recent Chrome releases.
What Google should be doing (despite the strong internal conflict against this - Android is run by the guy who invented ChromeOS after all) is fitting Android on PC's.
Now hear me out. I don't want the current Android to be put on PC's. That's obviously a bad idea, and it's been tried before and it doesn't work. Why? Because it's a terrible user experience having a phone (or even tablet) UI on a laptop. Nobody really wants to use Android-x86 project on their laptops, either.
But here's what Google can do. It can turn it into another "Android Wear" or "Android TV", but for PC's. What that means is that it takes the Android core, and all the Android compatibility, and then highly optimizes it for that usage mode.
Doing this will be surprisingly easy for Google, and about an order of magnitude easier than putting Android apps on ChromeOS. What they need is 3 things:
1) a taskbar - don't laugh. It worked for ChromeOS. ChromeOS really started being seen as a potentially good alternative for Windows when it got a taskbar, despite it having only shortcuts to web apps. But it helps greatly with usability
2) multi-windows - another thing that ChromeOS got later on. Initially it was kind of full-screen/multi-desktop, which wasn't that great of an experience.
3) Android apps that scale nicely to 13" screens or larger. This is actually already underway since they announced the whole material design stuff together with the Polymer library for web apps (which guess what - work on 13"+ PC's!) - so they have already "fixed" this problem for Android PCs, even if somewhat unintentionally. In fact, they are already doing that with these Android apps inside ChromeOS. Look at the picture they're using in the blog post. The app could look exactly the same way on an "Android PC". So why not do the same thing on Android, where those apps came from? This would have the advantage of getting virtually all the apps on Android PC's from day one of "Android PC" mode.
So the first two would solve the "OS optimization" problem, for larger screens, while the last one would solve the problem of the Android apps being optimized for larger screens. Again, this should be much easier than doing it on top of ChromeOS.
Do I expect Google to do this anytime soon? No it won't. Instead it will waste 2 years not doing this, while Apple puts iOS on a laptop, with advanced multi-tasking, a laptop that I expect to be much more successful than any Mac OS laptop, because it will be cheaper, and because an order of magnitude more people know iOS now, than Mac OS, so an iOS laptop has a much wider reach. After 2 years, they'll think "gee, maybe we should do that, too", but by then they will already be behind.
Android, with its 1 billion user base and still rapidly growing is also by far a bigger threat to Windows on the desktop than ChromeOS. People in many countries, especially emerging ones, are already familiar with Android, and have been using it as their "first OS". It's such a shame Google isn't going to take advantage of this, to push people to Android laptops. Oh well, they can't say I didn't try. Failing to bring Android on PCs will be on them.