If we can make a future happen where I can control software and data on a remote device, in a way that works for students, then sure. Otherwise, I wouldn't count pure access to the internet/web as actual victory for GNU/Linux. (Maybe as victory for education opportunities, productivity, etc., but tying that back to Linux is a very indirect connection.)

Either way, ChromeOS doesn't contribute to taking (co-)ownership of any of the above and encouraging the freedoms commonly associated with the use of Linux. Neither does it sustainably establish even the Linux kernel as pillar of the OS, it's just an implementation detail to be hidden and potentially replaced later. So why exactly should we look at ChromeOS as GNU/Linux having taken off for the casual user?

If you're defining Linux as the free-for-all open source community product, you're inherently defining why it will never take off for the casual user. That's not who that's for and that's not what the casual user does.