A trip into the mirror verse if its not already there. Just too see whom has control of it in 2409?
I'd definately like to see a plot arc revisiting either the delta or gamma quadrents at some point in time tying up some odd plot ends. What has happened to the dominon after their defeat some 30+ years ago? Did Odo manage to change anything when he rejoined the link? Did the Kazon factions ever stop their feuding? And what happened to some of the lesser spiecies Voyager visited and left a mark on?
Was the caretaker unique? Are their more like it else where?
While I don't doubt that could happen in this game at some point, it wouldn't actually be canonical, as, upon returning to Earth, Daniels shot the NX-01 to an alternate universe, stopping the Temporal Cold War before it started, which actually prevented the Xindi issue from happening. Therefore, while it's entirely possible that the Xindi do in fact join the Federation, the storyline presented in Enterprise (that they were in the Federation, actively serving on the Enterprise-J, fighting against the Sphere Builders) didn't happen, because the Temporal Cold War was stopped before it started, and because the destruction of the Sphere Builders in their time destroyed them throughout time, so the battle of Procyon 5 never happened.