I was thinking about this yesterday, and I believe people will underestimate the popularity of PvE servers this time around in WoW Classic.
The player base for Classic is getting older and doesn't have the time to spend getting ganked, camped, and other issues associated with a PvP server. They only have a few hours or so to play a day and don't want to spend half of it dead due to other players. Some will love and embrace the challenge but I think there will be a strong desire to play on a PvE server.
If you ever played the servers that should not be named, the PvP community is quite large and I could only find maybe 1 PvE only server. Most forums on those servers state that the want for a PvE server is very very small and not worth the effort to host.
In the essence of staying on topic, I believe that PvE servers will be very popular, and maybe to the point of being equal to PvP servers. What does everyone else think? Will it go the way of private servers and be 95% PvP or do you also think it will be roughly split down the middle?