A lot of the space behind the WoL building on its north side is now occupied by Cosmic Rewind. It might be conceivable to expand to its eastern rear (behind the former Cranium Command section), but there's an imagineering building in the way that would need to go and the road would also need to be rerouted (again). Maybe not impossible, but unlikely and also probably not necessary.
The WoL pavilion has mostly been gutted mostly down to bare metal and concrete inside. The former Body Wars and Cranium Command spaces combined amounts to approximately 40,000 square feet. If those two spaces could be combined together (which seems like it might be possible, that's a respectably large whole that could house a decently large dark ride. Especially if they use a ride system that is space efficient (as in something not trackless, maybe an omnimover or even just a traditional bus-bar like system). It's about the same square footage as WDW's Haunted Mansion or Ratatouille (not including the queue).
That also isn't really including the main "dome" lobby. Add that onto the size and the WoL pavilion is close to 85,000 square feet in total.