Gundam 00 ending is just right.
People who cannot wait for the second season should just satisfy themselves with Code Geass R2 or anything
This is not official, just some of my speculation
Setsuna and Allelujah, are still alive, gundams are done for, so its a new generation of gundams with solar furnaces
Tierra is dead, he said so himself, but since he is probably an android, maybe he gets rebooted
The girl with him in the end is probably Louise, so if that is true, then maybe Louise is one of the new Meisters, but again just speculation
As for the new UN squadron, that was Kathy Mannequin, Sergei Smirnov, and was that Patrick? Where the hell is Soma(Marie)?
Graham is possibly one of the squadron leaders of the new UN squad, and is now known as the 'blue comet' (jokes)
Tieria is alive. Watch the full ending and you see him hes not "really" an android, I don't think. Probably just someone like Alle and has been fucked with a lot.