I signed up because a friend asked me to. Since then I've just been deluged with 'requests' I think I have over 1000 unanswered ones, but I just dont WANT to'throw a x at someone' or 'send x a virtual drink' and all this, I don't have the time or the inclination, it all feels so artificial when I can just send them a real message thru email or IM. Note I'm not against online socialising or communication, just the level of forced feeling that facebook and the like heaps on me.
So no, I wouldn't pay, although I imagine quite a few people would, it would be a small percentage and I think they're safer sticking to ads, I doubt they could charge more than £20 a year or a couple of pounds a month, and they'd have to add a bunch of new stuff for that, and bring in armies of lawyers and accountants to deal with all the new problems.
The daft thing is, I STILL feel a bit guilty if I do log in, as I see the 1000+ ignored invites to do stuff, despite communicating with the people who sent them, and knowing that in the main, I'm one of a list who just recieved one part of a 'send to all' click.
Ah, I don't need this crap.
Sorry to be so negative, I know people who really love facebook, and might pay a small fee to keep using it.