There are a few attractions or defunct buildings in Tomorrowland that could get rethemed or reactivated, such as the Innoventions building or Magic Eye Theater, or BLAB and Star Tours, with minor disruption and an under-2-year timeline.
A larger, but still moderate scope expansion project I can see, which is to replace the Fantasyland Theater with an attraction, or even a mini-land. Specifically, I think with a Pooh 100 Acre Woods with updated attraction, honey-pot spinner, retail, meet & greet. The reason is that Pooh is a huge revenue driving IP for Disney but its placement is poor at the park, far from the young kids and grandparents traffic flow. At night, that's a dark and far-away destination from where these familes are spending time. And they're leaving money on the table retail-wise. I think a bayou fan-boats flat/water ride could ultimately replace Pooh in Bayou Country (solidifying the theme, something that's needed). And a reconfiguration of the back side of Bayou Country could allow a walkway from SWGE to circle around the west side of this new outdoor bayou-themed attraction, creating a second traffic-flow to a bridge to DisneylandForward instead of all traffic routing through the neck of Bayou Country. (This second traffic flow from SWGE is a lot easier around an outdoor flat ride than the dark ride show building). This is a 3-year project.
There is a need for a third attraction in SWGE to justify the size and drive traffic back there, and specifically a themed coaster is what is needed, in my opinion. A Jawa Droid Factory coaster could bring original trilogy IP to the land and bolster droid-merch appeal, plus filling it with animatronic Jawas is high reward/low cost. The Seven Dwarfs swinging gondolas could be used, or the suspended coaster type being used for the Monsters Inc. door coaster at DHS. This is a 3-year project.
There are two huge possible projects, one which would be a new IP land (like Frozen) where the Autopia/Subs/Monorail/PM spaghetti bowl is, and the other is an overhaul of Tomorrowland. Each would likely be 3 to 4 years.
All the above constitute all the notable "moves" I can imagine in Disneyland until DisneylandForward.
As for the next five years, I put the odds at:
- Retheme or reactivate an existing defunct Tomorrowland space or attraction: 75% (or 0% if a TL overhaul is planned in the next 10 years)
- Fantasyland Theater replaced by attraction or mini-land: 50%*
- Third attraction in SWGE: 30%**
- New IP land in the spaghetti bowl: 20%
- Overhaul of Tomorrowland (within 5 years): 15%
*I put the odds of this relatively high because it's a splashy project but actually pretty modest in cost and allows Disney to kick the can somewhat on bigger projects like the spaghetti bowl or TL.
**I put the odds of this relatively high because, in general, Disney needs to find ways to keep the SW brand alive and if the movies and TV shows are struggling, a new attraction is a valuable marketing beat for the franchise.