Yeah, I don't really see Nintendo being interested in Phoenix considering that AA is basically on its death bed at this point.
Like I said, we only got Banjo & Kazooie because of massive fervent fan demand. I'm not convinced Phoenix Wright is on that level.
I've never been convinced that B-K's inclusion rests wholly on fan demand. I'll repeat on this:
We have to remember that
are Rareware's most prominent characters (outside of the DKC characters, but that's Nintendo's property anyhow). Even after Sea of Thieves became a success and pretty much revitalized Rareware. Sure, one could hypotheoretically use a SoT Pirate (who fills pretty much a
:-esque role in game)...
but SoT does not have iconic characters the same way as WoW has (AFAIK). SoT would be very difficult to even properly market partly because of that to the Smash audience. Thusly, SoT's out (as an aside, if SoT has come out on the Switch or even Wii U in 2017 or before then it'd have a legitimate chance I'd argue).
As for other Rare characters... B-K is more major than Battletoads, KI or more mature ones like Conker and Joanna Dark. And Rareware was a consistent developer for Nintendo for 10+ years (arguably even 15). B-K's case was strenghened because of that status as "The #1 choice from a former second party".
Phil Spencer officially sponsoring the inclusion helped a ton. That's not to say that the fan-demand didn't have an important effect on the selection -
the fan demand absolutely did help a lot. I'm just not convinced it's the only reason.