Red Faction absolutely needs to come back. One of the best games for destruction. Red Faction: Guerrilla is still one of the best of all time, so hopefully we can get another open-world sequel in the future.
I also think both Patapon and LocoRoco should come back as PS Vita games eventually as well. When I think of the PSP I think of games like those. If not on the PS Vita then at least do something with them on the PS4 or something sort of like Tearaway: Unfolded.