What an understatement.
-Seaworld San Diego is the worst of all their parks- Whoever buys SW will try to either find someone to take it off their hands for nothing, or more likely- just shutter the doors and write it off. As for Aquatica San Diego- that actually could be sold off- but likely to someone local as there isn't another regional park close by.
So lets play the game that Universal bought Seaworld and what I would think would happen:
-San Diego is written off- animals shipped off to zoos/aquariums and the big ticket items to San Antonio. Aquatica is sold off locally.
I could see Uni or Disney wanting that property in SD with a change in the lease conditions. It would be a big rebuild though. I'm also not sure SD City would play along, although its not impossible.