We don't know that. I actually suspect that as long as both the hard coded transaction fees and the hardcoded block size limit are not changed the price of bitcoins themselves will in fact increase the block size at some exchange rate.
A reducio ad absurdum of that is, suppose tonight bitcoins skyrocketed to $10,000 per coin. For one coin one could not only budget a year of home fibre but also pick up a nice 8-core, 32-MB-RAM, 2TB-disk workstation/server machine and, at least if one were of the or a "me generation", then happily join the "moar size, moar size, moar size" brigade with an undertone of "I'm okay Jack, sucks to be you" directed at no third world resident in particular.
Sucks to be the guy who bought in at $9999, of course; had he bought in back when it was only two digit values of dollars though maybe he'd see it the moar moar moar brigade's way too.
Sucks to be the miner who sold their coins instead of holding them that magic night too, I guess.
But it is a market. Offer us enough dollars per bitcoin on the bitcoin exchanges and sure, we'll double the max block size. No telling at what exchange rate though of course, that's for the moar moar moar brigade to discover by making offers for coins on the exchanges...
-MarkM-