If Magic Kingdom were built today, it would likely not be themed to Adventure, Frontier, Fantasy, and Tomorrow at all. It seems like the directive from TWDC for their theme parks today is the Universal style of lands themed to specific properties. The irony is that Magic Kingdom as originally constructed presents so much opportunity for multiple IPs in each land, but if they built it new, they probably wouldn't go this route. I could see Frozen, Lion King, Moana, Toy Story, and Cars being the IPs they select for their different lands. It would stink, too.
In my opinion, a good theme park needs attractions that can stand on their own; otherwise, you either have rides with expiration dates (which need to be updated or rethemed) or rides that represent IPs that have become evergreen. At a certain point, though, a park that is themed only to the five franchises I mentioned above would become stale, and you'd have to add a whole new land or retheme an existing one in order to move the park forward. It's a cycle that Magic Kingdom as originally constructed could avoid because of its lands themed to general ideas rather than particular properties.
I feel like when looking at most of the Universal parks, there's going to be a time when most of the rides there will need to be updated or replaced because they are almost exclusively tied to IPs.
