So far there have been lots of smartphones and tablets running FLOSS but this year a new kind of gadget is becoming mainstream, the computer on a stick. The best one I have seen comes with Ubuntu GNU/Linux or Android/Linux and you can connect USB keyboard/mouse and HDMI monitor/TV. That should work for everyone.
Price? $199 Today. I don’t know what more anyone could want except perhaps Debian GNU/Linux on the gadget. This kind of thing can be manufactured for much less and I expect in a year or so it will be affordable by even a larger segment of the market for personal computing.
If there’s one drawback to this it is that it is too portable and probably would need to be glued down in places like schools. Another is that you need at least a USB hub in addition but it is still the smallest working computer that functions more or less as one normally expects a PC to function.