No... no I don't think that's right.
Just because Banjo has a big history with Nintendo doesn't mean he had an edge at all. Cloud... Joker... Snake. All of them were far more known for their Playstation status, but they got in due to popularity (or personal request in Brawl's Snake). Phoenix Wright's series, up until recently, was never on a competitor's console outside of mobile ports (bad ones might I add), so by that logic, he's basically confirmed.
Banjo got in through sheer fan demand. Don't you dare deny that. He's a third party character now, and that means he has to follow Microsoft's rules. I'm not saying a Resi character can't happen (and honestly, now I expect it), but all I was saying was that point 5 was weak in comparison and is more speculation. My perspective doesn't include that.
Banjo was a specific case that will never happen again. Stop comparing it to other instances, it is the one instance like it. I've been speculating Smash since before Melee came out, I know the demand for Banjo was always there. I was sad when I found out Banjo wasn't in Melee. Most Smash speculation fans were sad Rare got let go by Nintendo, and gave up hope.
I legitimately don't understand your point about Cloud, Snake or Joker. Resident Evil is a bit more tied to PlayStation than Nintendo as well, and people have wanted Leon Kennedy in Smash since legitimately the day Resident Evil 4 dropped. But like Cloud, because of a view that it was "impossible" for a character like Leon Kennedy to happen, most people gave up that hope.
When Snake was initially revealed in Brawl, the demand for Cloud was probably as big if not bigger than Sonic initially. But once "expectations" kicked in, people "realized the reality" is that Cloud "couldn't happen" but "Sonic must happen." Before people even had hope for Cloud... the Smash 4 dev team had realized "hey the demand for Cloud is probably actually huge"
which is why Cloud Strife warranted the biggest reaction for a single character in Smash history. A lot of people wanted him, but they all thought "that's impossible." Expectations aren't reality... that's one of the most important things speculation has taught me.
Banjo had a lot of demand but little talks about him until after Smash 4 came out and ended production. It blew up once we got K. Rool even more. Why?
Not because more people wanted Banjo now than before, but moreso because people who wanted Banjo realized Banjo had a shot in the past few months than all other points of time after the Microsoft's buyout of Rare.
That's really what these speculation "Hype trains" are all about... expectations, not reality.
(This is also why we have anti-fanbase form like for Chrom in Smash 4 and why a lot of people wanted Robin and Lucina instead but doubted those character's odds Smash 4; their speculation expectations were their Final Roster reality. This also had an effect that led to Chrom being in Ultimate ironically; people who had grown to expect Chrom grew to like Chrom, and wanted him as a clone for Smash 4 DLC and later for Smash Ultimate)