4 Things are going to happen post Naxx.
Spoiler Alert
- All Servers will progress to TBC
- Classic Stasis servers will open for people who want to Transfer their characters back to a stasis server of their choice.
- Fresh Classic servers open (as needed) (non character transfers)
- Fresh TBC servers open (as needed) (non character transfers)
This keeps the community the most intact and allows players to choose what they want to play while allowing blizzard to properly gauge true server populations.