I'm thinking 10-20 years from now.Maybe, I guess its tough to know at this point.
AR wouldn't replace phones imo because it'd be a worse experience. Screen quality on a phone will be better than the perceived screen quality of an AR phone for the foreseeable future.
Also I was thinking of this thread specifically for gaming. Will portable handhelds still exist with flat screens in the future?
I don't think portables will exist for much longer, mobile is become better and better for gaming and then you have solutions like Switch as well. I don't know if VR will take over TVs though, if it doesn't get enough support it could just die off again. I think the general market isn't really that interested in it, and its a hard sell without having people actually try it.