Quote from asap:
on a serious note, i believe fb board will agree to an offer to be acquired in the next two to three years by an IT major, i.e. apple, ibm, msft, orcl or goog.
most probably, price will be in the $10s area because the company still has a rich valuation now and they don't have any substantial growth potential going forward, given their business model. as far as the user base is concerned, they already reached a plateau from which there isn't room for exponential growth anymore, just incremental improvements.
fb should have came up with a subscription fee while they were the undisputed leader in the field w/o competition from any major, i.e. google. they could have asked like $10 per mo per user in 2009 or so, which would have lead to revenues above $100B per year in foreseeable future, given the lack of alternatives users had back then, like either your were on FB or you were dead.
but, instead, they allowed google to build up a competing offer for free and now they're stucked with an inefficient business model, while they've already reached important economies of scale, that haven't impacted the bottom line.
in sum, fb is very valuable, but not for the actual shareholders, but rather, for the IT majors lurking out there, which at the right time, will put up a fight to grab FB business. but, when that happens, the stock will be trading sub $10, so the final agreed price should be in the $10-$20 area, IMO.