I have a suspicion (haven't got much to back it up but hear me out) that the Switch may get two Smash games, one still in production and another one based off WiiU.
The other alternative being Smash Switch is very far on in production, and they're trying to keep the hype train a bit lower this time by waiting until it's mostly done to show.
The "Smash 6" job-listing dates back to April of 2014. That's almost four years ago - longer than any other Smash game's development-time, to date. Why would they split their resources so as to make two games, and then consequently split their userbase in ways that are inconvenient for both users and the business? For example, they will almost certainly want to offer DLC, and why would anyone try to sell DLC for two games simultaneously, by wasting time and resources on a port of a game that's almost half-a-decade old? It doesn't make sense no matter how you slice it.
Don't forget that Nintendo's policy these days is different to before - they now determine when to reveal things on a case-by-case basis. In some cases, they'll give an early teaser just to make sure that the information is out there, and in some cases, as stated
here, they prefer to wait until it's possible to show a game in action before they announce it.
The most likely scenario, to my mind, is only that the engine will be re-used - it's the most efficient way of bringing such a huge roster over, and we can even see a hint of it in Smash 3DS/Wii U, because they use an engine that was designed to scale across wildly differing architectures (the 3DS' ARM, and the Wii U's PowerPC), whether on battery-power or plugged into the mains electricity-supply - something that the Switch needs to do on one machine, rather than across two.
Moreover, the Nintendo Switch Online service launches in September. It's going to need a flagship game in order to convince people to start subscribing - after all, simply saying "You have to start paying for stuff that's been playable online on the Switch free-of-charge for 18 months, now." isn't going to enthuse anyone, not even people who are on-board with the paid online-service. Something like Animal Crossing is too relaxed and doesn't have online as a focus, and something out of left-field won't have a built-in audience, so something more traditional like Smash just makes sense. And if that's the game that they've chosen, then they won't want to muddle their message by having two releases.
Occam's Razor, and all that.
Is all that Smash 6 stuff actually confirmed, or is it all just rumors? It's been too long, I need a new Smash.
The article already contains the information that you're looking for. To quote the relevant part of it;
Something to note: While the original recruitment page has apparently been deleted from e-career FA, it doesn’t appear to be fake. Tatsuya Matsumura, a consultant who uploaded the ad, seems to still have all of his other recruitment ads live on the website, which includes career opportunities for other companies such as Square Enix, Capcom, Tecmo Koei, and various mobile developers.
Upon further research, Matsumura appears to have been in the business of a career consultant to connect developers and software companies with programmers and engineers since 2011. He currently specializes in getting people in touch with gaming and software developers, and has successfully helped the recruitment of over 2,000 people thus far.
Note, also, that the job-listing was posted
before it was
confirmed that Smash 3DS is officially considered to be the fourth installment (i.e., "Smash 4") and Smash Wii U is considered to be the fifth ("Smash 5"), which, for anyone who was keeping an eye on it for all this time, explained why the job-listing used the name "Smash 6".
What we have is this: Safe-bet claims, designed to look plausible because they're not unlikely, coming from the same associated group of rumourmongers who've previously given us such gems as the following;
- Ballot-winner Shovel Knight
- Multiple Ballot runner-ups also being released with Shovel Knight
- Splatoon The Enhanced Port Definitely Not A Sequel for Switch launch
- Second Switch SKU with more on-board storage, with the above as a pack-in game
- Switch only available in grey at launch, and white later
- Zelda delayed, 3D Mario is the big Switch launch-day game
- Switch's first year to be "port-heavy"
- Mario Kart 8 Deluxe has new cups
- GameCube Virtual Console releases (Super Smash Bros. Melee, Luigi's Mansion, and Super Mario Sunshine) at Switch launch
- No-frills port of Smash Wii U within the Switch's first six months
With the current claims about Smash Switch contradicting previous claims made by the same group of people, and I believe also made by the same specific person.
Versus a job-listing posted by a legitimate consultant known to have handled such listings for numerous developers, that was posted almost four years ago, at the same time that Super Mario Odyssey is known to have
begun development, and that Mario + Rabbids Kingdom Battle is
claimed to have commenced development, and a year earlier than Splatoon 2's development started, as Splatoon 2 was built from the
ground up in just two years.
I'll leave it to you to apply critical thinking and draw your own conclusions.