Will FF ever be mainstream?

So Nikon finally announced what the photography world had long expected - the D600. It pretty much was what everyone expected - slower burst rates than both the D7000 and D800, limitations on options (like a sync jack) but a nice 24 mp sensor.

What surprised some was the price - $2100. Now a month ago, rumor had it that the camera was going to be around $1600, and really put a full-frame option available for the masses. Instead, its announced price is still above the $2k threshold, meaning there will be a number of people who will turn to APSc cameras instead.

So my question is this - Will the full-frame sensor ever be mainstream?(Its probably the wrong word to use mainstream, but the market for FF is much smaller than the other smaller sensor sizes) Will a full-frame ever break the $1,500 barrier? And is there a market that it should? For camera companies, it seems like the answer would be no. Why would Nikon force a choice between an entry full-framer and its X00 line? Would Canon do the same?

Clearly Full-Frame has a market - but will it ever rise to more of a niche? It does not seem like we are close to seeing full-frame outselling the flagship APSc models anytime soon, and if they are limited in options, we ever will. And my thought is instead of trying to make full-frame cheaper, why not work on things like rolling shutter, or LiveView focusing?

What would you like to see improved or added before you would like to see a $1,500 Full-frame? Or is this what you want most of all?