I think the future of bitcoin is largely in the hands of the ASIC manufacturers. If they keep most of the ASICs for themselves, they may end up controlling a significant chunk (maybe even most) of the bitcoin network once the remaining GPU miners have left. We would then have a situation where the network's computing power (and most of the newly mined bitcoins) are concentrated between a relatively small number of ASIC manufacturers. If that happens, I could see it crashing the value of bitcoin, but it could be good for the scrypt-based alt coins.