Never underestimate a team leaving because of a building dust up. You L.A. fans should know that better than anyone else. After 1957 when Walter O'Malley couldn't get Brooklyn to help him fund a new stadium to find a new home for the Brooklyn Dodgers to replace the outdated Ebbets Field he packed up shop and moved to L.A. where the team is today. Just like that. He called their bluff. He's a hated man to this day because of that, but it happened. To compare what the magnitude would be of the Brooklyn Dodgers leaving town the best comparison today would be imagine if the Boston Red Sox left town. Honestly, Brooklyn was the second most profitable team in baseball after the Yankees. So I guess what I am saying, is that this can surely happen to the Anaheim Angels.
But will it? I doubt it.
That being said, that land is too far for a Disney park. This isn't WDW. They have land the size of the city of San Francisco. They've got monorails and buses and you never leave Disney property to get to where you want to go. Would it be a little anticlimactic to be taking a monorail - or a bus or whatever - down Kaletta Avenue to go to a third park? I don't know. I think it would.