I hope the next movie will do its best to ignore T3, if done right it could be a cool sequel/prequel. Too bad they can't have Micheal Biehn in it, they could have brought the thing full circle and had John send Kyle back in time.
It is going to be weird going from the guy who played John in T3 to Christian Bale. I think Bale looks much more like a grown up Edward Furlong than Nick Stahl did, Bale also has a much better look and style to play a character like John Connor. I also hope that if John's wife shows up in T4 she is a little less annoying that her portrayal in T3.