Alright, so I'm hoping I don't get too ranty with this comment. I've been seeing some things on this board that remind me of the old days of Smash 4, and it occurred to me that, frankly, I think far too many people view Sakurai as some sort of god. I want to cover a few things that some people might not quite understand.
Sakurai is not a Nintendo employee. He leads his own studio of Sora, which is
contracted by Nintendo to create Smash. Think of it as having somebody do a project for you, like a home improvement project. There are two parties involved...the owner (Nintendo with Smash, you with your home project) and the contracted group (Sakurai and Sora, the renovator).
With this business to contractor relationship, there is much to consider. If you're the business and having an outside contractor (granted, one you've trusted with this project a handful of times already) take on the project, there's no doubt that you would meet with the contractor and discuss what you'd like to see. In this case, there are many fans out there who believe that Sakurai has
100% unleashed control over the entire game. While I do not have proof otherwise, I simply do not believe this is the case.
I firmly believe that, at the very least, Kimishima would meet with Sakurai and discuss the direction both parties would like to see the game go in. Smash is no joke...it's going to sell extremely well on the Switch regardless, but the impact it has on Nintendo products around it is undeniable. Not to say Kimishima wouldn't trust Sakurai with his selection of stages and characters, but I wouldn't be the slightest bit surprised if, in 2016, the meeting more or less ended in, "Listen, the Wii U is dead. We want you to take a look at the future of Nintendo and what's to come. Obviously, maintain your thought process on what you've picked...you've rarely been wrong before. But this is simply what we'd like to see".
This loops into my theory that development started so quickly after because of the fact that the Wii U was a sinking ship after DLC ended, and Nintendo wanted to rock the boat with all their best titles on Switch.
As far as marketing, which is more effective? Including content that barely scratches the surface of your newest hotly successful console? Or including content from games that, despite being the successor to the Wii, went out without much of a wimper?
Now, this doesn't mean I think Sakurai is under the thumb of Kimishima or Nintendo. I simply believe they give Sakurai plenty of liberty, simply under the direction of the game. The direction of the game is discussed between both parties and they come to a sort of agreement.
The only reason I suspect they might try to ride the success of the Switch (granted it was 2016, but I think they had a plan) is to continue the momentum of the console. I think we could see a shift in character selection, so that rather than looking at the previous generation (because most of the previous generation was filled with the same usual series, or most series saw no development of new characters on Wii U), the roster looks to expand upon current history. That's more or less what I think will see, but I'll also admit it's what I would like to see.
Other thing I want to talk about...3rd party characters. You know who obtains the licensing rights to those characters? It isn't Sakurai. It's Nintendo. Nintendo does the negotiating of getting the characters, creating the amiibo, etc. Sakurai might open the door to asking about it, but he does little to no negotiating. I see this as a common misconception when fans say, "If Sakurai wants a character, he'll get the character". Uh, no. That's literally not how that works.
This is, again, why I think it's entirely viable that the contracts for Cloud and Bayonetta (if the decision to do another Smash game was already decided) might have been set to cover the following Smash game. I could be wrong though, as the contracts might have to be renegotiated per title.
Either way, I firmly believe fans put far too much stock into what Sakurai is capable of. Whether it's because they see the man as a god because he creates their favorite game (which I understand), or because they don't consider the parties involved, it's not so easy for certain characters.
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Basically, I would certainly not count out Switch characters. Kimishima has taken an aggressive strategy with marketing the Switch. Smash Switch, with Switch characters/titles being a focus, would only amplify that.
EDIT: Completely unrelated to the rest of my post, but I saw something about a Rex reveal. If he's in, the music to go with him absolutely should be Boss Battle II. Otherwise known as this:
I would lose my mind if this was the theme.
(Also, I think Argentum Trade Guild would be a great stage!)