The Terminator 3 comparison is interesting, and could be viewed similarly, but they actually got good talent involved with the production and had Arnold back, which was a step in the right direction. Now if they had gotten Antoine Fuqua to make T3 with someone other than Arnold, no one would...
If Disney were to go ahead and make a sequel without Pixar, I would sit it out. And also, I dont think that Hanks or Allen would do the films if Pixar were not involved, as I believe they were instrumental in the second film even going to theaters in the fisrt place.