Will GPU's make prime coin miners rich? I don't think so. Conversely to bitcoin, the higher the difficulty of the prime coin network, the lower the actual rewards will be. So, if someone creates a GPU miner that gets widely deployed, all that will mean is less coins are getting generated for everyone to share. Not even like Bitcoin, where the award stays stable for years at a time and then halved, and hashrate increases change the way the pie is sliced up; the rewards for primecoin actually diminish. Convert the whole network to GPU's that offer a huge performance increase and the block reward will tumble.
So no. GPU's offer no panacea, and would be hugely detrimental (i think). The only thing driving it is greed, where people (assumedly who have GPU's that are idled from the Bitcoin network) think they can get a leg up in primecoin land...
Someone talking sense at last! The whole GPU for Primecoin thing has been a disaster, no-one has been willing to develop anything for the coin because of this background idea that a GPU miner will turn up soon and instantly make us all millionaires/make the coin worthless. Isn't going to happen, people, Primecoin will remain a CPU only coin for a long time, mining at roughly the current rate. So let's get out there and build a useful environment around it.