I'm not sure if Disney buying out Hasbro would change anything, as far as D&D is concerned. Like the article says, the primary motivation for this would be to own toy licenses for movies, which makes sense considering tie-in toys make a lot more money than Dungeons & Dragons does (depressing, I know). Hasbro has a pretty hands-off approach to its subsidiaries and I expect that Disney will as well, especially for Wizards of the Coast. Magic: the Gathering's formula is pretty solid already, and D&D is barely worth their time.
On the other hand, if Disney does get involved in D&D, I think it would actually be a good thing. While undoubtedly evil, the WDC is also very competent. What's good for the business is good for the hobby. Disney could market the game properly (something Wizards has never been really good at), do research properly (another thing WotC has often failed at), and be better able to respond to sudden challenges (like the DDi fiasco back during 4e's launch).
It is pretty funny to think of a kid-friendly, Mickey Mouseified D&D, but Disney is as soulless and amoral corporation as they come. If they change the look of anything, it is because their calculations tell them it would sell better that way. Which, perhaps, is exactly the kind of thinking the Dungeons & Dragons brand needs.