You do know that Wisner "reverse" engineered the film holder and processor apparatus and has made several copies that are in use, and I don't think Polaroid cares about that. If Polaroid ever decides to cease making the film available, then that would be it. The Polaroid color film and print material is probably the most complicated silver-based emulsion technology ever conceived. Of course Fuji does make some in smaller formats.
In other words, I think anybody is free to make a camera/processor to utilize the Polaroid 20x24 material...but what is the "longer term" status of the film?? You do know that the costs per exposure are $75.00 or more.