The strongest pitch at BlizzCon was WoW Forever, I think.
It's finally cementing Classic as a format with its own set of disciplines, and I believe it'll draw a lot of players back from Turtle, Ascension, etc. which have seen interest in recent years.
I'd love to see Blizzard work with the community projects [0][1][2] that underpin most private servers to release first-party (or "blessed by Blizzard" third-party) engine tooling (the way they used to with games like StarCraft and Warcraft) for WoW as a whole.
Doing that would be a lot easier than continuing this cycle of having to revamp things every few years to keep pace with what their arch enemy (the private server community) is doing.
Some players would argue that private servers are where the most interesting ideas for the WoW franchise are coming from, and that Blizzard haven't made experiences that are compelling enough to justify paying their subscription to play on official servers for a long time. WoW Forever is probably changing that for a lot of people, obviously, but for how long?
Consider, also, solo creators [3] who want to work on passion projects (with no intent to hurt Blizzard's bottom line by running a public server and "stealing" their players with their own intellectual property.) Why should they have no support whatsoever from Blizzard to create new games/experiences within WoW?
It's worth remembering that entirely new genres of games emerged from the communities of earlier Blizzard titles, like tower defences and MOBAs. And they turned out to be famously missed opportunities for Blizzard. Why haven't they learned this lesson yet?
0: https://github.com/mangos
1: https://github.com/TrinityCore
2: https://github.com/azerothcore
3: https://www.youtube.com/@Yafrovon