Do you have any examples?
I've never seen (or heard) of that as being standard contract language. So long as the licensee maintains their status as a business (no matter who owns the majority of it's stock), the license should maintain. Now, if Universal Orlando Theme Parks and Resorts SOLD the parks to someone else (and not the company, as it exists), that would be different. I mean..that's one of the reasons you create the seperate entity to "hold" the resort...to maintain continuity of assets and contracts.
Again, if you're right.....every time the majority stock holder changes (be it institutional investor or private shareholder), or someone/something makes a significant investment in a company, the license grantor would be able to negate their licensing deal.
While I know that Universal Orlando Theme Park and Resorts is held by a partnership, and that brings some new wrinkles, I would suspect that UOTPR is still a corporate entity and not an LLC or LLP (and that seems to be borne out by their executive structure, etc). I'll grant that I'm guessing...since there don't appear to be available articles of incorporation/partnership for review. But the LLC/LLP is likely the holding company. At brass tacks, this is actually a 100% (private, probably) stock sale...provided NBCUniversal doesn't just gobble up the other 50%.
In your example with Marvel and Time Warner...the issue is that DC couldn't use their characters. Only IOA could. And TW couldn't significantly change the way they're being used right now..they'd have to stick to the terms of the contract. And they couldn't "impinge" upon the Marvel area with DC characters, or depict the two together, or Marvel would argue misuse and brand harm, and it would negate the contract.
Now, I haven't seen the Marvel or HP contracts first hand...so it's all speculation on my part. I know a pretty reputable web site broke the Marvel/Universal contract down after the Disney purchase and specifically addressed the issue of UOTPR being sold, and that even THAT would not break the contract.
HP...according to screamscape...apparently DOES have a clause in it.