If Banjo & Kazooie got in, at that point, I wouldn't care if Steve got in some time after, despite my feelings on how he wouldn't work as a good character. Because I got what I wanted and anything after that, I'm good.
But if Steve got in over Banjo? I've tried to internalize how I would feel about that, and no matter how much I try to remain positive... it's not good. This is also the feeling I would get if in the unlikely scenario B&K ended up as some kind of trophy, assist or otherwise.
If they both got in, it'd be like the former, and I'd be glad both fan bases were happy. I don't see both getting in the base, though.
Wish I could see Steve in a more positive light as most people, but I also have to be honest about my feelings. Banjo & Kazooie mean a lot to me, to the history of Nintendo, and within Smash speculation history. Steve would be the epitome of having a popular character only because they're popular, and that just doesn't sit right to me in how I view Smash.
I've also considered the scenario where Microsoft came like a package deal; Banjo & Kazooie character, Minecraft stage/assist. While I'd be disappointed given a stage/Gruntilda has so many great possibilities, I'd give up a stage so that both get representation in the base. I get sad when I see people reveling in only Minecraft content being in the base. The optimal form of representation should be what pleases the most people--and B&K fit as a character, while Minecraft fits as a stage.
If neither gets in, I'll simply be disappointed, but not furious as in the case of Steve over Banjo. Will feel like such a missed opportunity, but I'd strive even harder for DLC.