Hmmm...the possibilities, and whether they're good or bad:
Transformers at Disney World: yessssss
TF content on Disney Channel, or at least Disney XD: Don't really care what channel it comes on, but it'd be good for the franchise as I'm sure more kids watch Disney than the Hub
Disney Store toys, more Mickey Transformers, park exclusives: meh. I wouldn't be willing to travel to Florida every time a new toy comes out, these exclusives would be not unlike most Takara exclusives to me in that I'll only bother when they're available to me at cons and stuff.
Cons: More money to have bigger cons? Or maybe a Transformers section at Disney events?? YES
Disney possibly halting production of Prime for whatever reason, or Masterpieces, or anything good:
Please, I don't know why they would, but still..no.
A Transformers/Pixar crossover: Could anything bad possibly come from this? They can put Optimus in Toy Story!
Disney now owning both Lucasfilm and Hasbro: Doesn't exactly seem like Hasbro has a hard time for getting rights to toys or anything, but certainly nothing bad can come with this on the star wars side.