Taking this as "What would you like to see WotC do that they probably won't do of their own accord, and neither will anyone else?" (which is to say tha the lots of Eberron goodness I'll be snapping up is pretty much a given)
Two really long-term licensed projects, which would require getting licenses straightened out
- Launch a Harry Potter RPG concurrently with the paperback of the final Harry Potter book (this assumes Rowling's preventing one right now to avoid spoilers, rather than because she's got something against RPGs in her world)
- Launch a second edition of the Wheel of Time RPG concurrently with the paperback of the 12th and final Wheel of Time novel (because the first edition needs some work, even if it's got some great ideas, and there won't be spoiler problems)
I'll join the chorus asking for more Star Wars stuff, especially a KotOR-era sourcebook (ideally time this to launch with KotOR 3, if such a game is in the works).
Something between the 1-level Basic Game and the three core rulebooks, as a more complete introductory game.
That ultimate D&D computer aid that eTools was originally envisioned as? Build it.
Resurrect or create or license a setting for d20 Modern, and support it with 3 or 4 hardcovers a year.
Resurrect or create or license a setting for d20 Future, and support it with 3 or 4 hardcovers a year.