So I've just seen that a Samsung Chromebook has been released in the States for $900. It looks very cool and also has a 4k display, not sure how the battery is on it compared to the other recent launches. I think I would prefer a device like this over the more expensive laptops plus it has the ability to be put into many viewing modes just like the Flex.
I guess with Chromebooks, you would have to be on an internet connection most of the time, and you can't run most software you find on a laptop on a Chromebook. But they were more secure than a laptop since they only allow chrome web store (and maybe android) apps.
With a laptop, you can play more graphically intensive games (assuming you have a powerful enough laptop.
That's just some of my thoughts about Chromebooks vs Laptops.