I'll continue to use all of my older games, so long as they work. I still play LeafGreen a lot, and that's several generations out of date, so I think I'll keep playing generation IV as well. I also still have a lot I want to do on HGSS, in particular, and I really love Johto (I would stilll play GSC a lot, if the batteries on all three games hadn't died), so that's definitely an incentive for me to stick with gen IV.
So far, I've noticed that the generation that's out has very little effect on which game(s) I play. When I have time to play games, I tend to alternate, and frequently prefer older games to newer ones, so I'll certainly continue to play gen IV.