I have heard this rumor for a while now that they are expanding so I went off and did research a little while back and found this on a site. Its from Jan 2000.
As part of the proposed upgrade plans to the WDW transportation system, a brand new TTC will be built. While information is still sketchy, we do know that it will be in a different location to the current TTC, and will interface the new monorail expansions and the other 2 transport systems (one of which is a light rail system). Progress on this project is well forward, ground clearing and drainage preparation is already underway.
On the monorail expansion we have be informed that current plans show routing to 5 major parks?!? It appears that the monorail will link all parks and the TTC, with Downtown Disney and the resorts being linked by the remaining 2 new transport systems.