Yes, it's by far the popular rumor with plenty of signs pointing to it. We are talking about it more in the 2023 thread.
As for long term speculation, the area of the current train station and Flooded Mine is where I'd see another major "refresh" project in the medium term future. FM is obviously ancient, though it is a treasure and one of the best attractions in the park, IMO. SDC is terrible about maintaining things though, and they have been letting it literally rot apart for a decade now. Some great employees gave it their best to keep things running as smoothly as possible, but most are gone now. I don't think it will make it much longer without intervention, and there's no one left who would take up that charge.
They'll probably replace it with some flashy high thrill attraction with a gimmick and market it as a "family attraction". Maybe that Gerstlauer coaster we almost got years ago...