I'm actually glad we're on this topic because I don't think I've ever gone into the business logic of my six pack predictions and why they make sense in my eyes. A lot of people seem to think I just go with things because of rumors but, honestly, I think pretty in-depth into things before I lock in an opinion, sometimes to the point of overthinking things. That said, I want to go into my 6 company predictions since January:
Nintendo- Pretty obvious and a big reason why I was harping so hard on the likelihood that 6 would be Nintendo even before Season 2 was officially a thing. Nintendo using it's DLC to promote its own properties is definitely a "no ****" sort of line of thinking.
Square Enix- The history between Nintendo and Square is very interesting. Amazing relationship during the NES and SNES days, creating several games that are still considered the best in the JRPG genre to this day. Square then bounced to Sony starting with Final Fantasy VII and, not surprisingly, Nintendo was PISSED especially when FFVII was deemed an instant classic right off the shelf. In a professional businessman way, even Yamauchi (Nintendo's president until 2002) more or less said that Square Enix could eat his hot salty nuts until the sun exploded and the resulting N64 and GameCube days show why.
The N64 and GameCube are pretty much a desert for good JRPGs (and a big reason why Tales of Symphonia was such a big deal but more on that later). In one console generation Nintendo lost Final Fantasy and Dragon Quest to Sony and they were pretty upfront about their bitterness until Iwata started making honest efforts to patch things up with the major third parties that jumped ship. For the sake of brevity, Iwata's incrementalism approach worked and Square and Nintendo were back on good terms. Fast forward to the Switch and now Square is not only porting games like crazy but making the first high quality console JRPGs for Nintendo since the SNES. Needless to say, this is a huge deal.
Based on this, I don't think Nintendo and Square are done yet when it comes to Smash. Like I said, Nintendo now has the first brand new Final Fantasy, Dragon Quest, and Square IPs on a Nintendo console in 20 years. Square pretty much corners the market on JRPGs and a Japanese company like Nintendo wanting them on their team is a no-brainer. Sony no longer has a monopoly on the genre and it's a huge business shift in tone.
Activision/Blizzard- The biggest Western developer in terms of revenue with enough iconic franchises you can name on two hands. Yet another company that wasn't particularly Nintendo loyal and mostly just flung over half assed ports until very recently and the relationship keeps getting better. Franchises like Crash and Overwatch are pretty obvious IPs that you want in your camp but so is the often dismissed mobile Goliath known as Candy Crush. The benefits of strengthening this relationship are about as upfront as you can get.
Namco- Like Ubisoft, Namco is one of the few third parties that's never really left Nintendo and has been one of its stronger partners since the GameCube. The relationship, however, could definitely be better and there's two franchises that Nintendo could definitely benefit from getting more support from: Tales and Tekken. Again, JRPGs and traditional fighting games are two genres that Nintendo often loses to Sony to do netting either or both has very obvious benefits.
Capcom- Capcom is probably the most iconic Japanese game company aside from Nintendo. Capcom has so many iconic IPs that it even flexes this by literally having a franchise called Capcom vs because there's so damn many. Capcom's loyalty to Nintendo, like Square, has a long and complicated history that's only really gotten back to the SNES glory days very recently. I strongly believe that Ryu in Smash 4 was basically Nintendo celebrating Street Fighter, the biggest traditional fighting game franchise, being back in their camp. Nintendo has wrangled over a good number of big Capcom franchises since the N64 days but there's one big prize that people often discount that has been a Sony megaton for almost two decades: Devil May Cry. Like Bayo in Smash 4, Nintendo has also struggled with having "mature" games in their camp forever so getting DMC to join the Nintendo party is definitely worth pursuing.
Microsoft- Nintendo and Microsoft haven't exactly been shy about it. A lot of their working together in the past couple of years has basically been a good ol' holly jolly **** you to Sony. The relationship is definitely quid pro quo up the butt because the two cover each others' weaknesses really well. Microsoft has a hard time appealing to kids and has a laughably bad install base in Asia meanwhile Nintendo's online infrastructure is kind of ass and, until very recently, had a super hard time getting "mature" genres like FPS and Western RPGs. The relationship is still young but the benefits have already been very obvious with plenty of room to grow. This is part of why I see Banjo as merely the beginning because you have two gaming juggernauts that have clicked extremely well in a short time and are both committed to tag-team-teabagging Sony whenever the opportunity comes up.