I hope that Universal sees how popular this topic is and how many positive comments have been made because they NEED to get going on this.
This is PERFECT for UO right now. They've been desperate to change Toon Lagoon, so they can retheme it to Nintendo fairly easily and relatively cheaply, at least compared to the money spent on Transformers, Kong and the Harry Potter stuff. And they can make a bigger deal about it in advertising than they could with an NBC Museum. They can focus on Mario, Luigi, Peach, Donkey Kong and/or Yoshi for the rides, and just have others like Link and the Pokemon as walk-around characters. Make an attempt to put a Nintendo show in the theater.
Down the road, if the show isn't a big hit, they can remove the theater and add in a Mario Kart D-Ticket (side-by-side racing AND interactive). If this is all popular - and why wouldn't it be, especially compared to what's in Toon Lagoon now - then they can retheme KidZone very cheaply to Pokemon (with a new entrance to ET away from the new land) and they can take those characters out of Super Mario Land. Then when they open a third gate, they can open a Hyrule land. And the best part of this is they can have a Nintendo land in every park and, unlike Harry Potter, it won't seem like they are overdoing it. Super Mario Brothers is extremely different from Pokemon which is completely different from Legend of Zelda. If they are kept out of each other's domains, they'll feel like three completely different IPs.
This is even better because it allows Universal to have "off-years" where they don't have to spend $100M+ every year, which means we could get something of worth every year instead of museums and walk-throughs. For example:
2016: Kong at IOA
2017: Fast & Furious at USF
2018: Toon Lagoon/Mario retheme at IOA
2019: KidZone retheme at USF
2020: Add Mario Kart to IOA
That's something at each park every other year and doesn't even include other rumors like the Twister replacement, the Star Trek stuff, the Ministry of Magic, Jurassic World attractions, Seuss Landing expanding, Krustyland expanding into the empty lot next to the Simpsons Ride, Men in Black being rethemed or the possible retheming of Hulk and the retheming/replacement of Dr Doom. Some could obviously happen at the same time - Ministry of Magic could be done during a Toon Lagoon retheme, Jurassic World during a KidZone rehaul.
In fact, Nintendo fits so well into UO's problem areas that every USF IP rumor of the past couple years can now be expanded on and moved to the rumored third gate: Star Trek, a third Harry Potter land, a third Nintendo (Hyrule?) land, The Hobbit, World of Warcraft, the Kaiju from Pacific Rim (and possibly Godzilla), and who knows who else Universal is talking to?