A version of 5e that lets me do solar expansion to transhuman science fiction. Including cyberwar and space opera. Future 5e!
Arcana of the Ancients, can help you.
I would love a Big Book of Complex Traps. Every encounter where I have combined complex trap features, with monsters, has been fun and memorable.
Module pieces like pre built traps or scenarios saves DMs time. I think it is an under served design space.
I use my old Traps and Treachery books, in 5e all the time. Often times without much modification.
I can never get enough monsters, so I am fine with another monster book.
A Short adventure anthology is fine with me. I would love to get something weird, inspired, and well put together.
I would love to get a 5e AD&D: Tweaks and different visions of the existing classes, balanced with 5e, but intended for games with more of a “
This one goes to 11” attitude, and more
gritty rules modules
enabled.
Combine this with an adventure path, and WoTC can demonstrate how different themes can be modeled with 5e.