When I think about the future of TL it makes the most sense to me to abandon the "futuristic" theme altogether. The longevity of any futuristic concept is and will always be very limited, which is what I believe to be the core of the problem in terms of TL's appeal.
When looking at DLP's version of TL: Discoveryland, as well as Tokyo DisneySEA's Mysterious Island I think that they've been really successful at depicting a specific vision of the future as it would be imagined by people 100-500 years ago. The theme is romantic and charming while still maintaining that sense of vision and adventure, and another important factor is that it will never look dated in the same way the the current TL's do.
TDS Mysterious Island:
If it were up to me, I would re-theme all of TL to a more Verne-ish steam punk sci-fi theme, gut Autopia and build a replica of Disneysea's Mysterious Island - including Journey To The Center Of The Earth - which everyone agrees is amazing, and perhaps re-theme finding nemo to 20K Leagues Under The Sea.
Not that I believe that any of this will ever happen, but considering the constant buzz about the future of TL, what would you guys think IF they decided to go in this direction?