It'd either be Mii costume or character, but I do think there's a chance for him to be playable:
- Epic Games loves to collaborate with other companies and do crossovers
- Fortnite is on the Switch, it even got bundled with the Switch. That's Nintendo trusting that the game alone would be popular enough to sell help sell their console.
- Fortnite has become one of the most popular games in recent times, at this point everyone has at least heard about it, and it still has hundreds of millions of active players.
This, to me, seems like the perfect recipe for getting invited to Smash. I personally don't like Fortnite, but the game can easily make its way into Smash. It's extremely marketable, and there's no chance Epic Games would reject Nintendo if they asked.
Fortnite is a contender, albeit it's very difficult to judge how likely it is. Nintendo very likely found no shortage of third parties (big and small, Western and Japanese) who would love to cooperate with Nintendo re: Smash. Like
3BitSaurus
said, Nintendo could go for another huge Western third party just as easily. I'm also of the opinion that Chief / Steve / LoL are a bit more likely since they have a clearer case, especially with the music.
Still though, Jonesy does have a legitimate shot: Fortnite's heavily based around twitchy reaction times (no, not just a pun) and its arcade-y fast-paced construction mechanic has helped it stand out compared to its BR competitors like PUBG and Apex. That could easily translate to a Smash moveset. Also, Fortnite can lay a claim to helping establish the BR as a genre - PUBG has a stronger claim here, but Fortnite's contributions shouldn't be ignored either. And the BR genre's not going to wither and die any time soon, Fall Guys and Mario 35 prove that.
One could argue that Fortnite's case is strenghened because
Knives Out (mobile BR) is mega-popular in Japan, and thus Sakurai and Japan at large is familiar with the BR genre. Combined with Fortnite's propensity for crossovers meaning that a lot of Japanese have seen their collabs with Marvel, Star Wars etc. Although one could likewise argue that Fortnite's case is weakened because
Knives Out overshadowed it. And to my very limited knowledge, Knives Out hasn't been brought up in the Japanese speculation scene at all. Nor Fortnite - meaning that if Fortnite was indeed chosen it would likely catch a very large number of Japanese by surprise.
That does bring up another question:
Venus of the Desert Bloom,
Ayumi Tachibana, if I may ask, was the whole "
Palpatine's EP 9 opening speech in Fortnite's Star Wars event" widely covered in Japanese media and forums? I know that Star Wars has been really popular there, so that's why I'm asking.