Purely my opinion here, but I think it would be interesting to see them take a more generic approach to the island. Instead of making one movie/game property the entire theme of the island, why not use a location/country that could incorporate multiple properties over time.
Think of it as a larger World Showcase pavilion, but with a few rides and shows. Disney has yet to pull the trigger on the addition of various countries, so why not take advantage of that and add it first? Or just make your own version of a country that is in World Showcase. All licenses aside, think of having a UK themed island that houses a good Hobbs & Shaw ride, a James Bond show, a few pubs, or even just a generic race through London type of ride?
Idea B would be to keep the non-IP theme of Lost Continent, but maybe you change it into a different environment. If Universal decided to turn the island into a snowy environment, I think there could be some really enjoyable, original content. You could make a dark ride that travels through a blizzard with run-ins with wolves, yetis, etc.
These are all just spitball ideas. I just think that we get too caught up in trying to create the next WWoHP, where everything has to be tied to one property, when ideas that aren't so IP driven could still work, and provide for far more flexibility, long term.