I think I'd favor the possibility of restoring it to the 1964 configuration.
An interesting idea for replacing the final scene, though, might go something like this:
1) Hire voice actors to replicate the current voices.
2) Dress the characters in the final scene in classic clothing that could fit in 1950 or 2050: Crisp shirt, a fine suit, a classy dress.
3) Incorporate video screens into the background of the scene while retaining physical props.
4) Change the script as follows: Begin the final, fourth scene sometime around 1964, and mention the World's Fair in NYC. Then, slowly and smoothly change the video screens in the background to show the house and neighborhood as it might look in 1980, then 2000, then bring it into the future of 2020, then 2050. The actual physical props on stage—the appliances, the photographs, the electronics—with a little Imagineering trickery, could be replaced with newer technology as the scene progresses. For example, when a character on one side of the stage is speaking, switch out a prop on the opposite side of the stage. Stage magicians use a similar form of distraction to accentuate their trickery. They will overemphasize a certain gesture to distract you from a more important, but less pronounced, gesture that is essential to the magic trick. Little by little the appliances and general look and feel of the house will change from 1964 to 2050.
5) The result is a dynamic scene that pays homage to the original 1964 configuration while postulating a future based on the present. Video screens, which form the windows of the house, could show Boeing 747s in the sky... then as the scene progresses, the Boeing 747s give way to space shuttle blastoffs, then advanced Concorde-style aircraft and even Virgin Galactic-style spacecraft. The rotary phone could be magically transformed into a desktop computer, then a holographic sort of computer that projects an image onto dead air. The house will magically progress before your very eyes in a dynamic, organic, futuristic, and historically sensitive way. Every once in a while a character will mention that time flies so fast while you're having fun—that it's now 1980, now 2000—wow, where did the time go?—now 2020, and already 2050! Welcome to the Future!
