Everything must eventually change, evolution.... I know change hurts sometimes, but it's just gotta happen.
I have very serious reasons why I don't think they should mess with the ride, in that manner. If anything, they should bring back the Tesla lightning effects (technology has come a long way since the ride was created, I'd find it interesting to see what they could come up with) and the troll area could certainly use some plussing.
However, overlaying it with a mediocre movie...meh. Build a new ride, I'm all for that. But, there is no reason to fiddle with this one outside of making it better.
If their "integration" is as wonderful (and I use that term very loosely) as what they did to Pirates, I will not be pleased.
Change doesn't hurt when change makes things better. Tossing characters into a ride that doesn't need it (it still pulls ridership). Could they do it well? Perhaps. Or they could toss in Olaf randomly throughout the ride and replace the scary trolls (who are suppose to be scary, it's a MAJOR part of the ride) with the Abominable Snowman and some of the smurf...er...trolls from the movie...bad.
Change hurts when it's not needed, or poorly thought out.
For example, slapping the Nemo ride into seas wasn't a terrible idea, but completely eradicating the Seabase Alpha storyline was. I'd be the first to say that Turtle Talk with Crush was an excellent addition (though, the theatre needs a refurb...it's showing it's age). The Nemo ride itself has an amazing queue, but the ride itself is disappointing. They could have put a lot more thought into that modification of the pavilion...but, really, they didn't put much thought into "story" (for all their lip flapping about how that is important) at all. And it shows.
I am aware that my opinion will not sway Disney one way or another (and, at this point, this is just a rumor)...and that doesn't bother me. But, I have a very pessimistic view on what Disney will create, and it's not because of what they could do, it's because what, over the past decade, they have done.