Another thing that may bode well for our duo. This is all conjecture, though, but we're bored so I've decided to share it.
One of the reasons Banjo never felt likey at all was also Sakurai's apparent apathy towards Rare stuff. Especially after how Smash 4 treated DKC, there was all the reason to think that Sakurai just wasn't a fan of Rare's games at all.
But if you think about it...
-Sheik's side B back in Melee was straight up taken from how Simon uses his whip in Castlevania IV
-Ike's final smash has always been inspired, if not kinda ripped-off, from Cloud's Omnislash
-Zero Suit Samus' redesign in Smash 4 owes something to Bayonetta's fighting style
-Smash Ultimate's menu design is apparently inspired by Persona 5's menu design
Of course, later Simon, Cloud, Bayo and Joker all got in, and it turned out that Sakurai was a fan of all those franchises all along.
Now, if we look at Duck Hunt, it's obvious that the inspiration must have been Banjo-Kazooie. The dog and the duck were never even paired in the original game, and the way they move and attack in tandem is very reminiscent of the way bear & bird do it.
So what I'm trying to say is, Sakurai may secretly a Banjo fan, ahah.
Well and of course, if he has some passion for a franchise, it's more likely that it will get included in Smash.