My issue with changing act 4 in efforts to modernize it is two-fold.
First, because of the previous attempts to modernize the show, the flow from act to act is odd jumping 60 years from the 1940s to 2000-ish after acts one through three only being 20-year jumps. To push act four even further into the future would mean something like a 100 year jump, and I can't believe that would flow at all from a storytelling standpoint.
But more importantly, I don't see how it is important for the Carousel of Progress to be some kind of "window to the future" any longer. Does ANYONE see the show to get a sneak peek into the future of home appliances? Some people like the music, others see it as special because it is one of Walt's attractions, others like taking a nap out of the sun and heat, but I suspect very few have EVER looked to the Carousel as a source of futurism. The first three acts were always a classic Disney-style "fond look back", so it isn't like the attraction hasn't been trading on guest nostalgia from day one anyway.
I would much rather see the show restored to look and sound as close to what Walt actually built as much as possible and leave the future guesswork for other more logical locations. Regardless of Walt's original intentions, the nostalgia we have for the parks and our wishing to have stronger connections to attractions Walt helped develop is far stronger and more important than continuing to tear apart an original, classic attraction.
Yes it is completely ironic, but in this case I think progress is the last thing the Carousel of Progress actually needs.