I don't expect a port for RE5 before RE6 or even at all. It'll probably cost Capcom the same amount of resources to port either game over and RE6 has a better chance of selling and at full price due to being newer. Economically, it makes more sense for them to just port RE6.
With this announcement, I'm already planning on getting the game on PS3. However, Capcom can convince me to hold off for the Wii U version if, say at E3, Capcom announces that the Wii U version will include a Separate Ways-esque side-mission and some other bonuses which would be paid DLC on PS3/360. Would that piss people off? Sure but that's the price of getting the game sooner. That would be the reverse of the PS2 RE4 announcement and I appreciate irony.