Eh... honestly, I don't think the parks need to change much at all. Universal is Universal. Disney is Disney. They are 2 different animals that really excel in their own unique ways.
That being said, the only things that I could see MAYBE warranting some changes would be some more calm/dark type rides for younger people, those not really into the thrill rides (AKA... your party's bag holder)... and those wanting to take a break from spinning/thrilly rides and relax a bit.
Oh... And maybe more classic movie-making/Classic Universal stuff in the Studios park. I sort of miss the Boneyard and Hitchcock/Murder-she-wrote attractions for the simple reason that they were fun things you could do that really helped with that "You are in the movies" sort of vibe. Something along such lines in the Universal Studios park would also probably help bring back it's actual Studio feel even though it's not really used for filming much anymore. (Considering 4 of it's (current) 7 sections were/are designed as movie backlot/set areas, It could help with regaining that Theming element without completely redoing the park)
Honestly, if you wanted to compare, the New York, San Francisco, and Hollywood areas are all much better detailed and cohesively themed than MGM's backlot street if you ask me.