Best guess:
With SWGE pulling crowds away from an overworked tomorrow land, imagineers are hard at work planning Tomorrowland 4.0 at DLR.
Once avengers campus is completed crowds should ideally abandon Tomorrowland altogether.
I would imagine Tomorrowland, almost entirely to close once avengers opens. Probably following the subsequent holiday season just to accommodate crowds.
Star Tours:
Will be re skinned - re themed into another space themed attraction - as a budget overlay like guardians, Wall-E seems most likely to me. It makes little sense to keep a Star Wars attraction outside the realm of the new land. I wouldn’t entirely close the door on a non ip based simulator ride like Epcot’s mission space either.
Space Mountain:
Zero changes - will likely remain open during land refurb via overflow walkway access behind the plaza inn.
Autopia:
Scrapped - we can drive go carts at any boomers or mini golf in so cal.
Submarines:
Hiatus but returns mostly unchanged. Difficult spiral staircases reworked to allow linear boarding. Entering from the front and exiting from the back would eliminate the excessive boarding process requiring all passengers disembark before new guest can even start boarding. Combined with the new 3 sub load / unload station should solve the capacity issues plaguing this attraction.
Astro blasters:
Vehicle repairs / replaced. Overall attraction is in disrepair. It could be eliminated entirely. They have not fixed anything since the 50th anniversary.
Innoventions show building:
Will become the queue / station and multiple pre show rooms housing for a new attraction based on the new Pixar film onward- while no details of the film are known - title and trailer may suggest that in some way the film could be futuristic as evolution and growth seem to prevail in the trailer “times change”. Indoor story telling can take place on multiple levels of the enormous structure. Outdoor thrilling sections can utilize the huge footprint from autopia. I would imagine an Intamin or Mack rides multi launch coaster, both companies have a solid reputation with WDI.
People mover tracks:
I truly believe they have not removed these tracks for a reason, besides being cheap. These tracks - in some form will be used for something. I’d like to see an attraction based on past future present - travel through the worlds of space in the wall e and space mountain attractions - travel though the now in the Forrest and sub lagoon - travel through the worlds of imagining the impossible with buzz Lightyear and fantasyland views. I really think it could be epic if the ride vehicles were extraordinary like encapsulated in semi transparent parabolic dome where a projector could paint a world for the rider mixing reality around them and imagination layered in.
Tomorrowland Terrace stage will be completely removed to Re-home the Astro orbiter - finally allowing free flowing traffic in and out of the land.
The motion theater under space mtn queue can be opened up to provide live entertainment and stage shows to a semi open air audience by removing the facade facing the plaza. Movie previews can be done at the opera house. There’s no reason that auditorium should be used for previews and not be an attraction itself.
These are all just my imagination!