I don't necessarily think there's evidence for him showing up. But I think that so many planets have aligned to allow his inclusion that if he dosn't show up in Ultimate's DLC, I would be quite shocked. I mean, look at what we know.
Phil Spencer's comments actively supporting Banjo in Smash (meaning he'd be a the negotiation table if the two companies talked)
The Smash Ballot bringing him to the attention of Nintendo Execs
Evidence that Microsoft is going to be bringing a whole host of content to the Nintendo switch
The lack of use of Steve in Minecrafts general marketing
De confirmation of Master Chief
Banjo's continued use in MS marketing
The success of the Crash and Spyro remakes, as well as Mario Odyssey.
Erdrick's Japan-Only appeal making it likely that a character that appeals to western audiences would also be chosen to compensate (see Chrom and Dark Samus)
That one leaker who said that one of E3's characters would be part of a whole host of related announcements with "huge ramifications" (circumstantial, I know)
The way I’ll respond isn’t meant to nitpick, I just want to address each point clearly!
1)Phil Spencer showing interest- Perhaps, but
many developers would like to see their characters in Smash. That would effectively mean that a developer wanting their character in Smash makes them more likely. Unfortunately, it doesn’t. Otherwise Shantae and Super Meat Boy are likely as well.
2)Smash Ballot/ Popularity- this is a reasonable point, but there are plenty of other characters that have popularity still.
3) Microsoft content on Nintendo platforms- They may be collaborative wither each other, but considering Sony and Microsoft are collaborative as well (to a lesser extent) seems to me like it’s a move to expand their options in the industry. I don’t really think collaboration means that Smash automatically comes up. Seems more like shoehorning it into the conversation.
4) Lack of chances for other characters- It might look good for Banjo if Steve and Chief are out of the way, but that assumes a Microsoft character is being chosen in the first place. I
personally think the chances of that happening are overrated.
5) Success of Crash, Spyro, and Mario Odyssey-I’m...not sure why 3 games being successful and having little to no connection to Banjo or Microsoft is relevant to Smash.
6) Erdrick as Japanese-only appeal: this is entirely fabricated by western fans to make a western character more likely. There’s evidence to suggest that Square wants to extend exposure of DQ to the West because it has always struggled in the West, which, in addition to the legacy for gaming that the Dragon Quest series holds, makes Dragon Quest a reasonable pick. Chrom and Dark Samus were popular picks (Chrom moreso worldwide), but they are also first-party echo fighters, which is unfortunately not quite the same situation.
Banjo arguably has some things going for him (i’d be delighted if they added Banjo & Kazooie). But I think the chances of Microsoft getting a character in Smash is overrated, and hinges specifically on the collaboration, which is mainly when the hype/speculation over it started.
The reason I put it that way, is because it seems to me that the largest basis of it lies on the collaboration. As in, demand for a Microsoft character is only currently high because of an expectation, leaks, and the ballot.
Basically expectations and wants should be more or less hyped responsibly.