When it opened in Queens, my grandparents, who did live through that first scene, rode and enjoyed it.
Disagree completely. The 20-year one-generation jumps worked great in 1964. Adding a 50+-year jump destroys the whole idea of "progress." Especially when the last scene is a horribly dated retro-prediction of a 1999 that never was. In my ideal head canon, they'd go to 50 year jumps--keep the first scene, update the third a bit to better reflect the 50s, add in a third ca. 1980 ("Called a V - C - R ... we can watch movies at home whenever we want! And in the kitchen, some new fangled oven, a 'microwave'...), then the current day or 5 minutes into the future. But I can live with this proposal, if Imagineering can pull it off. I'm just not sure they can pull off the whimsey required.
That said, maybe the idea of celebrating American process really is best left in the 20th Century, and we'd be better off with a Stitch dark ride. Sadly. looking forward to a bright future is no longer a shared value that defines us.