So here is my take on what I think Frozenified Maelstrom is going to look like- you board boats that look suspiciously like viking ships (just cleaned up a little), in front of a newly painted frozen themed mural- then you go up a lift hill with a projected eye of papa rock troll giving you 2 secs of back story.
Then you enter into the "arriving for the coronation" scene, some props will be re-used, including some of the vikings as "arriving guests".
Next you enter the snow scene with Anna, Kristoff, Sven, and Olaf- you'll see the ice castle in the distance. Remove puffins/polar bears and you're good
Next scene you'll see the familiar fiords, but it will have a can of cheap spray on snow liberally applied. Our friends the trolls will be long gone, but you'll see Elsa- who hits you with ice powers (aka the fiber optics from Maelstrom).
Then you go back over the falls- but once again the falls room will have been liberally covered with fake snow and the "peaking troll" will also be history.
Then you'll descend into the final scene, where the oil rig is gone, but you see Anna and Elsa embracing, the end, happily ever after- Swen, Kristoff and Olaf will be in the background.
Then you'll roll into the port of Arrendale, just remove the sailboat and the last few promotional signage, and you're golden. Since most of the theater is now a snaking queue, you pass through just a small roped off area to exit. OR- optional bonus ending if the whole ride becomes FP+ only- you'll enter into a "Let it Go" sing-a-long on constant loop where the movie used to be.
If Disney wants to do this on the cheap, all I can say is- you're welcome (and if this really happens I'll be totally horrified!)