That said, I don't believe the Chromebook lock-in. It's just chrome and the web, which you can get on literally almost every laptop/pc sold today. Should Microsoft be concerned that you don't need windows as more and more things move onto the web? Absolutely. They should be doubling down hard on the gaming ecosystem (which atm still requires windows for certain games) as their hold is eroding week by week.
Step 1 get rid of adware
Also it's a joke to run OpenGL on Windows ARM (it fully works just no one makes it anything easy)
My x13s laptop can almost run A tier games without a fan which is impressive but it really feels disconnected and unsupported from all parties making these laptops.
I'd be interested to see a legacy-free Windows, stripped out like LTSC, with no 32-bit binary support. Especially an Arm64 version with no x86 binary support.
How lean and mean could it be in the 2020s?
I think this is an Americentric view. As far as I can tell, the mass adoption of Chromebooks for education is just the US, which is 4% of the world population. And in this particular case there's little reason to believe it will suddenly propagate everywhere else - the US education ceding has been going on for years, and yet it's still confined. It's not like the iPhone which started in the US and within a few years rapidly gained ground in Japan, then Europe and so on.