I think Spencer's trip to Japan is just an extension of him trying to reach out to Japanese developers and publishers, as he had mentioned recently. It doesn't say that much about Banjo in the base game because--why would he be going this late in development?
But I feel like the evidence, however indirect, still gives me hope:
- Spencer acknowledged the possibility of Banjo in Smash in 2015, the same time as the ballot
- Most polls from that time show Banjo & Kazooie as highly popular, and we know from Sakurai's statements the ballot has informed some of the roster
- Rare/Microsoft has gone back to Banjo's N64 design--I can't see Microsoft doing that on their own, but I could see Sakurai going back to the N64 design
- Verge says Minecraft is in--I cannot see Sakurai going to a rival company without getting a character, Banjo most likely (depends on when talks began tho)
Everything seems to line up to me. Of course, I'm biased. And I've tried to be as critical as possible to avoid giving in to confirmation bias. But I feel like out of all characters being speculated, Banjo's one of the few who haven't been directly rumored that has all of that going for them. I still have low expectations given Sakurai's recent statements, but I hope there's still room for the bear and bird to come back home.