Well they could do but only as much as 24 and then we'd be back to the same format that we had in USA94, or they could have 20 teams with 4 pools of 5 teams. If there are going to be weaker host teams like there will be on 2008 and like there could be in 2012 if some of these countries put together a serious bid:
Azerbaijan, Greece, Italy, Romania, Russia and Turkey are all interested in hosting Euro 2012. Poland and Ukraine and Croatia and Hungary put forth joint bids.
I'd like to see 24 teams and have a tournament like we saw in 12 years ago in the States. 6 teams of 4, 2 best third place teams also going through. UEFA would love it I'm sure, will be interesting to see if it's on the agenda.