Speaking with MTV Multiplayer, he said:
[quote]
“No one should sleep on that franchise. That’s a tremendous franchise for PlayStation in general. We’ve had two that are the top two sellers on PSP right now. So, there’s definitely continued conversations with Rockstar on all their brands. That’s nothing that’s left the PlayStation family.”</blockquote>

Like Koller says, the first two games were smash hits, still selling strong to this day. The question is begged, why wouldn't Rockstar put out another?