Why get rid of Toon lagoon and keep Kid Zone first? Toon Lagoon at least has amazing water rides. The Kid Zone doesn't have jack crap. What I'm saying is they're better off keeping TL for the moment and deciding later on what or if they want to replace it with something else. That old Kid Zone is in the most NEED for something exciting, new and fresh(hence Nintendo).
Because Toon Lagoon has way more space for shops and restaurants which, in case you haven't noticed, tends to be Universal's obsession lately. KidZone is a tiny area - basically the size of Diagon Alley minus the ride building and the London waterfront, which means very few attractions or very few shops. A multi-character free-for-all in that tiny space will not do the IP justice. If Universal sees the excitement this announcement has created, they will certainly start blue-skying ALL possible ideas: replacing KidZone, retheming Toon Lagoon, replacing the Lost Continent, replacing San Francisco, filling the empty lot between The Simpsons and MIB, third gate land, etc. Of course, Universal could still be going after The Hobbit for its Toon Lagoon replacement, but that doesn't mean Universal Creative isn't currently working on ideas for ALL of the soon-to-change areas. (Personally, I wish they'd just retheme Toon Lagoon to Bikini Bottom, which may not make tons of people happy but the recent movie did remarkably well and the series is routinely one of the top shows on cable. IN RERUNS. Besides, it's all water rides, and SpongeBob lives in the water. And I want to eat at the Krusty Krab!)
I hope they have GREAT ideas for KidZone because there will be MANY problems to overcome shoving Nintendo into this area. There are so many things Universal MUST do back here, or the whole thing will be a bust:
1) THEY MUST HAVE, AT MINIMUM, A HIGH-QUALITY D-TICKET RIDE! Copying Radiator Springs Racers or any other Disney ride is NOT that ride. A motion simulator is NOT that ride, especially in a park with TWO of them. A racing coaster with GREAT theming could be that ride. (Even better, add in an interactive videogame-like element, like four buttons for each rider - a banana peel, a turtle shell, a star and a bob-omb. In each station appears a Simon-like sequence - banana/star/bob-omb/banana/shell - and the riders all have to punch their buttons in sequence. The fastest racers on the buttons race through a themed outdoors area ahead of the other racers. Win the most legs, win the race. Rerideable and no movies!)
2) THE ATTRACTIONS CANNOT UNDERWHELM! Hogsmeade soared thanks to the addition of the innovative Forbidden Journey. Diagon Alley is even more detailed yet doesn't seem to be as beloved as the original, possibly because Gringotts hasn't risen to the level of Forbidden. Disney is constantly taking old ride systems and theming them to new properties - a Marvel Rock 'n' Roller Coaster, Iron Man Star Tours, Soarin' Over Pandora, Pirates of the Avatarean, ugh. Universal needs to continue to be the innovator.
3) THE THEMING CANNOT UNDERWHELM! This cannot be Toon Lagoon 2.0, with differing Nintendo themes sitting side by side. It must be elaborate AND immersive. I don't want to see Pokemon anywhere near a green pipe. I don't want to see Link amongst the toadstools. Nintendo is a BIGGER license than Harry Potter and it needs to be treated as such. One hopes Nintendo has their own JK Rowling, who is able to give a thumb up or down to Universal's ideas.
4) THEY CANNOT EXTEND THE LAND INTO THE EMPTY LOT! It's already a trek to get to the end of the KidZone, they can't have a dead-end path that winds all the way to the other side of the Simpsons Ride! From the main entrance of KidZone to the back of KidZone to the middle of that empty lot is over a quarter-mile. You can't do that to visitors. You can build the entrance to a ride IN KidZone and the adjoining ride into that lot and it'd work. Another possibility is to build the Nintendo land in the empty lot - which is HUGE, about two Diagon Alleys INCLUDING the Gringotts building - and build the new ride (Mario Kart!) in the current KidZone area, with the start of the ride still in the empty lot area. (This actually works GREAT for keeping Animal Actors and ET separate from the new land. Personally, I'd rather see a non-movie Simpsons ride that will excite people more than a few years down the road, something no motion simulator has EVER accomplished.)
5) THEY CANNOT SIMPLY RETHEME THE KIDDIE RIDES! There isn't a single attraction here that can be rethemed without lessening the Nintendo IP. Nobody gets excited about kiddie coasters or play areas, but parks need them; Nintendo doesn't.
6) THEY CANNOT GET RID OF THE KIDDIE RIDES! The ONLY way they can satisfy #5 and #6 is to move the kiddie stuff elsewhere, just like USH moved the kiddie stuff to Super Silly Fun Land to make way for Harry Potter. When rumors started about a large attraction taking over KidZone, questions immediately surfaced asking where the kiddie stuff would go. Obviously, the only place is the Krustyland-adjacent lot. Add a REAL Simpsons ride as a backdrop (a Mount Krusty flume-coaster for this water-starved park!) and they can put several kiddie attractions back here that wouldn't ruin the Krustyland theme. (MIB can be rethemed to Treehouse of Horror to extend the Krustyland theme around the corner and the Mario Kart track can hide nicely behind.) Of course, building the bulk of the Nintendo land in this lot also works, but if that is the solution, I want to see more of a Nintendo Fantasyland with NO crappy flat rides and maybe ONE elaborate play area. But I'm still shooting for a Mount Krusty flume coaster for this lot!!!
7) THEY CANNOT TAKE FOREVER!!! They have a lot on their planned development plate for the immediate future: Kong in 2016. Fast and Furious. The Ministry of Magic. Jurassic Park/World attractions. Toon Lagoon redo. They CANNOT Avatar this thing!
As has been said before, nothing is set in stone at this point and there are lots of things that can affect Universal's plans. Thanks to Diagon Alley, the two parks will be very close in attendance at the end of 2015, which means they will most likely alternate big new attractions until one of them falters. If Kong opens in 2016 and underwhelms, then UO will need to focus on something big for IOA in 2018. If Jurassic World rakes in the big bucks, then the Discovery Center overhaul will probably be moved to the front of the line. If the film underperforms, all we have left here is a Toon Lagoon or Lost Continent retheme, and getting rid of Toon Lagoon is a much higher priority for Universal.
Meanwhile, over at USF they're waiting to see if F&F wows 'em at USH. If so, it'll be coming to USF in 2017, meaning 2018 should put the focus on IOA, regardless of how Kong does. F&F requires its own land retheming and I don't see them closing down all of San Francisco and the KidZone at the same time. If F&F underwhelms at USH, then USF will need MAJOR help, which could be Nintendo OR the Ministry of Magic. While I don't really care about MORE Harry Potter, it's a proven commodity; Nintendo is still an unknown. Fortunately Jurassic World and the Fast & Furious attraction both open this summer, so some of the question marks will go away before fall, which is when they need to start making decisions for 2017 and 2018. I wouldn't expect any movement until then, so all this is just for kicks and giggles until we know more.