I've been watching since '77 and that was truly one of the trancendent moments of the entire run. I am firmly in the camp that The Curator is a future or final Doctor enjoying his retirement. With Galifrey back, I would think that the day may come when The Doctor can be relieved of his duties looking after the universe. You'd think that eventually the Time Lords will realize that "intervention" like the Doc's been doing alone is worthwhile.
As for The Curator, he's too good a character to never see again. However, any future appearance should be special, not a run of the mill ep. Maybe a Christmas Special or something.
How great is it that, in 2 minutes, Tom Baker creates a second memorable character for this series? It also wasn't lost on me that he was the only classic Doc not to participate in the 20th anniversary and was the ONLY classic Doc in the 50th. The damage to the Vortex has been repaired.