Watto's chance cube was fixed in the first place, although whether or not Qui-Gon was aware of this does have some bearing on just how dishonorable his force-push really was.

Wookie Wedgie, I'm not so sure about Qui-Gon not getting killed until Episode III. It had always been implicit that it was only Anakin and Obi by the time the lava pit duel rolled around. Maybe he could've stayed on in some other capacity once Obi-Wan started to train Anakin? Or maybe (and this is something I just thought up just now) he could've stayed in the shadows after Episode I as some mysterious figure and then had his big reveal in Episode III and then gotten killed by Anakin.

Gaffer Tape does have a good point, though. Even without the Greedo scene there are way too many cameos making the PT feel more like one huge homage instead of a continuation.