First of all, I would like to admit that I know very little about buyouts.
If Verizon/Apple bought Disney, I see one of two things happening:
1) The quality would decrease. It has been said earlier in this thread that Verizon/Apple know nothing about theme parks. My knowledge of economics is limited, but I know you can't run a theme park like a tech business. However, unless the parks became extremely unprofitable, they would be shooting themselves in the foot to close them. The parks are the crown jewel of the Disney brand. Even if they did nothing but maintain the parks, they still would bring in money. While the event of a Disney buyout is nearly impossible, even if it did happen, the parks would not close.
2) Quality would increase. If Apple/Verizon were smart, they would realize they know nothing about the parks and bring in people who do. Hopefully, they would bring in people who actually care about the parks rather than bottom line. I would think the parent company would let the parks do whatever, as long as money kept pouring in.
This all being said, the event of a buyout is highly unlikely. Like others before me have stated, it would be more likely that Disney would buy Verizon or Apple.