There's already transportation via water taxi. But I agree, a trolley running end-to-end ala the Red Car Trolleys at DCA would be awesome and add some visual pizazz to the area.
But without a trolley, they *must* make the water taxis a more prominent and viable means of transport within DD. The dock for the marketplace (the busiest section of DD) is tucked away and hidden between Cap'n Jack's and Rainforest. If the marina is going away, this would be a great opportunity to relocate the Marketplace dock to where the marina is now and add more signage to make it more visible to people and realize that you can hop on a boat to go all the way to the other end.
On the West Side, they also need to increase the visibility of the boat dock. As it is, you get to the far end, see that there's nothing beyond House of Blues except Cirque and people turn around. The signs for the dock are these teeny little signs on the light posts, and you have to walk down around the far end of HoB. Either they need to increase the visibility of the dock here with signs, or move the dock closer to the center of the West Side to where the little sitting area is along the water between Bongos and Wolfgang Puck.
-Rob