Supposedly, the funds that would have been put fourth for another park are being spent on the major additions to EPCOT, along with perhaps the other additions, though I don't know if that's really the case. Personally, I'd rather have this than another park, because a new park would not be likely to have many attractions, AND much of the money spent would be on other design and building aspects besides attractions.
Also, Walt definately did not have plans for 7 parks, though I've heard that rumor before as well. In fact, he onlt planned for one park. The rest was a new concept, dominated by a prototype city, with the name of EPCOT- Experimental Prototype Community of Tommarrow. Things were added to change and re-change the plans, which is why WDW seems a little disorganized.
This is a great site to find out about Walt's plans for EPCOT and WDW. Watch that amazing video... Walt's last production!!