Um... well, you could look at the original Winnie the Pooh stories and compare them to the present day Pooh franchise (which, fwiw, is beloved in our family).
Assuming Disney's approach to Harry Potter would be similar to how they've handled Pooh Bear, here's what I see...
In this alternate universe J.K. Rowling would have to give up all creative control to Disney, because Disney rarely - if ever - settles for less than total control. Harry Potter's continuing adventures would become a TV series, featuring a Harry who never ages past 11, and who is drawn in a big-eyed animation style, to appeal to families with young kids.
Eventually he'd be ditched altogether for his adorable daughter - no more than 6 - who would lead toddlers on magical, educational TV adventures. Because the Powers That Be would conclude - after having cutesied up the franchise - that their core audience was little girls, and little girls relate better to another little girl, not a boy with a weird scar on his forehead.
Voldemort would become indistinguishable from Gargamel (from the Smurfs) - sort of a hapless, incompetent, non-threatening "evil" figure who constantly gets his comeuppance at the end of every episode. And then all the good guys laugh at him.
At the parks, all the little girls could get their pictures taken with Hermione. Ron and Harry would be featured at a character breakfast. And there would be a gentle boat ride through the TV version of Potterland, with animatronic characters singing at you. The toddlers will love it.
And hey - when you get home, you could decorate your nursery in a Baby Potter theme!