I think at best, we need to make sure the amount of players who are joining is equal to the amount of players who are leaving. I think that players being able to find tables for games they want to play is important, so too much variety can be harmful. I also think that players leave the game due to boredom, as there is nothing new to experience or think through.
Personally, I would love to see expanded thrown out the window and see sets created that continue the Movie block- like a movie block +. These sets should have erratas for the strongest and weakest of cards in Movie block, as well as create new cards that will cause old cards to once again become playable.
That, or we'll keep moving forward with Second Edition once MarcinS completes his move!