I'm sorry to tell you this, but we're already there. So much of USH has changed in the last few years. Here's the park map from August, 2013:
And here it is again, with everything that has been altered or removed marked out:
The north side of Baker Street will be remodeled over the next few months as we lead up to the opening of SLoP. The park is undergoing a rapid transformation, an Evolution. Who knows what the park will look like six years from now? Or by the 2028 Olympics?
To be honest, some of the changes have been good, and even great.
The way the park looks currently is perfect, in my opinion. Updating and retheming Jurassic Park to Jurassic World was wonderful, and the other additions have also managed to reintroduce certain aesthetics the park had lost:
The metallic look of T2 was brought back by Transformers.
The fiery indoor set look of Backdraft was brought back by Walking Dead.
The magical, nighttime fantasy look of E.T. was brought back by Harry Potter.
And the other, family-friendly additions have also been fine. Even Despicable Me since, to be fair, Universal fully owns that.
Ultimately, what makes all these new additions suitable is they come from story-driven mediums, whether movies, TV or, in the case of Harry Potter, literature.
Nintendo is not story-driven, but gameplay-driven. That's why it feels so off to me. I don't think people think fondly of Mario and Luigi for the stories they told, but for the hours of fun gameplay they offered. Plus, the park now has a plentiful array of big-eyed, cartoonish characters walking around (Minions, Simpsons, Kung Fu Panda, etc.). Adding Nintendo characters to that is just taking the park into more of a Disney-ish direction which, I have to be honest, painfully annoys me.