Personally, I feel like it's just too much Star Wars with the franchise now having a dedicated land. I wouldn't be opposed to a third land inside of SWGE, but a ride on the outside just makes little sense now.
I do agree that the OT characters still should have their place though. I think it's very possible that Batuu could work as that place, but they would need to back off of all of the talk of it being set specifically within the New Trilogy. A speeder bike coaster as a third attraction would be fun and could call back to the original trilogy (of course with Tron coming to MK, this type of coaster wouldn't be as unique to the resort anymore upon opening).
To bring it back to Star Tours, I think we're looking at it sticking around at least through the 50th, so 2022 would be the earliest movement would occur. I think there's two possible things that will happen: Either an overlay that can be shared with Disneyland (Incredibles, Big Hero 6, etc) OR complete demolition as a part of an Echo Lake project, possibly with something to do with Indiana Jones. Just educated guesses, but Star Tours itself staying I don't think is something that will happen long-term.