There are 3 instances where Phil name dropped the duo.
1st via Tweet in 2015: "I think it would be cool if Banjo was in the next SSB DLC. We've worked with Nintendo on Rare IP before,
no issues"
2nd Via Interview about Battletoads in 2016:
I know I get questions all the time on would I ever like to see Banjo in Super Smash Bros. and I’m, like, “yes, I would do that in a second”. And certain people think I’m saying that as some sort of PR answer and I’m, like, “why wouldn’t you?”.”
https://www.ausgamers.com/features/read/3564591
3rd is Via tweet in 2018: "Yep"
Burn these into your memory, lads and ladies. Dont ever lose faith.