It is a longer walk than you think. We walked from the Contemporary to MK once because they said it was a nice walk and not that far... well it sure felt like a long walk which is probably why we only did it once an didn't see any other people when we did it. I think it is about a half mile walk from Contemporary to Main Gate at MK... From WL to Contemporary as the crow flies its about 2000 feet so you would basically be walking a mile to go from WL to MK... Most people probably don't want to walk a mile when they know they'll be walking all over the place once inside the park. So I really don't see them making any walk way for what would likely be a very low number of guests.
As for the island, assuming they could make a quick and cheap bridge to the island and then over to the Contemporary... that would really just be asking for lawsuits when people got eaten by alligators since that island is uninhabited and people would likely go exploring as you mention which is great if you are prepared but most people are not prepared for exploring in wetlands inhabited by the likes of alligators and water moccasins. So that would only leave the option of turning it into a restaurant and shops... That's doable but it would be very expensive because the island is just that an island. But restaurants and shops would require water and sewer services that would cost a lot to connect to since it is an island. So yes they could do it but the cost would likely be so high that the question would be why? They have Disney Springs for the shopping, so they have no need to create a new shopping area... They could make a restaurant but if that was all they created on the island it would mean that the island would have to charge insanely high prices to cover the cost of creating the place.
In short I just don't see them having any reason to do what your hoping for.