Companies like Facebook should be expected to pay back to the local communities. Building more housing is a good way of doing just that. Obviously, the bigger your business is the more responsible you need to be.
Japan isn't the only country facing this issue re: demographics but their problems are more pronounced because they don't want to take in the necessary immigrant labour to fill their demographic holes and are more resistant to the needed social changes to address weakening family units.
Well, they are paying back by giving the people work and such. Like I said before, for me, the problem lies with the local businesses and real estate market who want to profit off of those companies. As employees of those companies are paid more, those local businesses want to make more money. Because why go for low prices when you can catch bigger fish instead? Underlying that is the real estate market which is somewhat based on supply/demand (but also speculation). If that model would change to something like "first-come, first-serve", it would be vastly different. But then again, that wouldn't make much money now, would it? If they really expand the cities to keep costs down, we will definitely end up with mega-cities (like what is happening in China).
Yep. But they have the advantage that they are way less adverse to robots. So if they can create useful ones in time, it will work out for them. Here, refusal in such matters will definitely lead to problems. But then again, old people need social connections anyway, so who knows how all that will end.
But one major point, rural depopulation, isn't addressed by any country with these problems (as far as I know). Part of the reason for that will probably be solved by technology but that won't be enough and it will probably be too late by then anyway. (Also, it ties in nicely with the issue of space in a city.)