I'd rather see a new Soarin' film at Epcot, but I think that Al Lutz and AV are on the right track.
If Disney management wants to put a Soarin' type attraction in Epcot, they have two choices:
(1) Put in a proven crowd pleaser, without spending millions on a new film
(2) Spend millions more on a new, unproven film, just to fit in better with one of the current Epcot themes.
Unless a sponsor wants to pay for option 2, I can't see Disney management choosing anything but option 1. And, these days, there doesn't seem to be a stampede of sponsors waving cash at Disney.
The idea that Oriental Land Company (OLC) would want to sponsor a Soarin' Over Japan attraction is just wishful thinking. OLC doesn't sell anything in the United States. Yeah, they might gain a small number of additional US or European visitors to TDL and TDS, but their return on investment would be awful.
So, then it becomes an issue of how to make Soarin' Over California fit into Epcot. I think they could pull it off, even if it is a stretch.
If you think about it, Soarin' Over California is about land use. You soar "over" various types of agriculture, urban spaces, and natural settings. With a proper pre-show setup, the attraction is about land that just happens to be in California. Therefore, it could go into a new building addition on the side of the Land pavilion.
Do you remember that for many years, you could see "The Wonders of China" in Tomorrowland at
Disneyland in California? There was no effort to fit to a theme. So before anyone says that "sanity will prevail on this one," just remember that putting Soarin' over California into Future World at Epcot is a lot more sane than other attraction decisions that Disney has made over the years.