Here is one source that mentions the rumors of a GMR replacement. It also has some neat facts about the ride:
http://allears.net/tp/mgm/m_movieride.htm
For my part, I want the attraction to stay, but like others here, I feel it needs a thorough upgrade. At the very least, the incredibly cheap-looking Busby Berkeley scene in the beginning needs to go. I think a tribute to the great early movie comedians like Charlie Chaplin, Laurel and Hardy and Harold Lloyd should go in there. This scene with Lloyd from his short "Safety Last" would make a great visual piece:
AAs of Chaplin, Laurel and Hardy and perhaps Our Gang (the Little Rascals) could be grouped below it. There could even be strobe lights on the figures that suggest the flickering of early film, and all of the AAs could be painted/dressed in black and white.
I also think the Tarzan scene either needs to be upgraded majorly or replaced. But I have no idea what that replacement should be, probably because of too many possibilities...