According to the StatCounter, Linux on the desktop has continued to rise and remains above 4%, with this being the healthiest it's ever looked on the desktop.
Chromos will definitely be big, but its limitations mean that it won't definitely not be able to just take it over.
And given that it relies on Linux apps to run non Android or web apps, AKA desktop apps, I'm quite happy if it grows—Linux development becomes encouraged.
Yeah I kinda doubt it too. However there's a real possibility for them to eventually replace it with Android, once they get the desktop mode finished up. Especially given how they've started caring about costs lately, maintaining two OSes with a lot of overlap might trigger some axing.
Chrome OS has a simplified desktop experience. I think people who don't do technical work and that grew up with Chrome OS will continue to use Chrome OS