Considering that the games for the PS2 continued to be developed well into the life of the PS3, it all hinges on the user base for any platform. I can create something meant for a defunct platform if there's a demand. If however there isn't and things switch over rapidly to next gen then yes those might get the attention. That's unlikely given the state of the economy and the questionable nature of any new product. Also, typically at launch units are in a rather short supply so devs are reluctant to put all their eggs in one basket. The PS4 and One may have a larger volume of units available, but demand and use will determine how quickly a past gen game's life diminishes.
I want a PS4 but only might get it right away based on a lot of things. I may one day want an xbox 1, but that has bigger question marks attached to it. When I get a PS4, I'd consider Defiance or just continue playing it as I do now. I won't play it exclusively since I rarely do that with games now (and Killzone-Shadowfall is calling my name). But I will play Defiance in one form or another. I'm interested in seeing where they go with it and I have fun playing it.

