From what I've heard as other posters said they do need some work.
They can't totally tear them down and start over because that area is considered wetlands now. So if they tore them down, they couldn't build anything new.
I have taken the boat between DD and the Port Orleans resorts many times over the past couple of years and have never seen any indication of anyone staying there even corporate types.
The electricity and HVAC is probably maintained in those units to help keep them up, so that's why you see lights in some of the units.
If the electricity and HVAC was discontinued they would deteriorate more quickly.
Back when they were open, they seemed like they would be inconvenient transportation wise.
I made a couple of bus trips around the old Disney Institute to Downtown Disney several years ago and the bus that serviced the Treehouses went to all stops at the Disney Institute, then swung through the Treehouses, then to Typhoon Lagoon, then on to Downtown Disney.
Don't know what their park transportation was like, but the DD transportation was a Pita.