I think we'll just have to wait and see who has the properly functioning crystal ball. I think you're entirely missing the point of Dropbox, Flickr, online chat, etc. And you're also imagining a very unlikely future in which anyone, other than a handful of nerds that already know how to run a real web server, thinks, "Ooh, I want to host web pages on my own computer!" The idea that this will become dramatically more common, rather than as quaint as growing all of your own food, is, to me, absolutely absurd.
Even ignoring the fact that the idea of "your computer" is becoming less and less a big box that sits on your desk and more and more a tiny device that you have in your pocket or your bag; and ignoring the fact that we'd really like for computers, even the big ones sitting on our desk, to sleep when not in use so we don't chew up so much power and produce so much waste; and forgetting about the fact that someone has to actually write the code for all of the magic functions to address the problems you've proposed Unite can solve (and for a proprietary platform that about 1% of users use); and discounting the chicken and egg problem that in order for this to be easily useful across all of your devices you have to have Opera on all of your devices. Even forgetting all of these, huge, probably insurmountable even to a company the size of Microsoft, problems, Opera Unite still doesn't solve any big problems that really effect users.
Even ignoring the fact that the idea of "your computer" is becoming less and less a big box that sits on your desk and more and more a tiny device that you have in your pocket or your bag; and ignoring the fact that we'd really like for computers, even the big ones sitting on our desk, to sleep when not in use so we don't chew up so much power and produce so much waste; and forgetting about the fact that someone has to actually write the code for all of the magic functions to address the problems you've proposed Unite can solve (and for a proprietary platform that about 1% of users use); and discounting the chicken and egg problem that in order for this to be easily useful across all of your devices you have to have Opera on all of your devices. Even forgetting all of these, huge, probably insurmountable even to a company the size of Microsoft, problems, Opera Unite still doesn't solve any big problems that really effect users.