Having offline apps is game changing because not everyone has access to the Internet all day long, and doing tasks like image and video editing on your laptop will be much easier and faster than using web services.
This is not game changer. It is exciting and might help grow the Android ecosystem. I just hope Google learned from the Honeycomb fiasco.
I'd be pretty surprised if you won't be able to side-load Android apps on ChromeOS.
It's cool, but not game changing.
The cheapest notebook is about US$200.