Since Blizzard released WoW Classic, players are discussing oncoming patches and possibilities to keep this project alive for a very long time without ruining the whole experience.
The community is split in a couple different oppinions on that case.
Some want Classic WoW with new dungeons, new areas etc. and some want Blizzard to release The Burning Crusade or even Wrath of the Lich King.

What do we want?
We want to stick with the idea of Blizzard releasing World of Warcraft Classic+.
We don't like TBC and we hate WotLK. We want Blizzard to improve the cast World of Warcraft and use the given possibilities like Hyjal.

Why do we want it?
Most people think that introducing the expansions TBC or WOTLK would split the community. There are a lot of ideas on how this could happen. Some ideas involve splitting servers into Classic and TBC realms. This would split the community leaving the small playerbase with half guilds and lost friends. Also it would let the classic servers die slowly. We love World of Warcraft as it is. We love not having flying. We love not being able to use the Dungeon Finder and having to walk to dungeons. We love searching in trade chat for groups. We love it, as it is. This is the game we started loving.
And most likely: We just don't want to play a game that's getting re-released over and over again. We want WoW Classic to be the game we always wanted to see but never got. We want Mount Hyjal to be accessible and being a actual raid. We want to see unfinished lands coming alive.

Any ideas on how this could look like?
More detailed plans, wishes and ideas can be found in a wonderful article by Johannes Amstrup Andersen. It's explaining how World of Warcraft Classic could introduce expansions for Azeroth without breaking the immersion or introducing evil TBC or WOTLK.