I'm guessing you consider double dipping fine given some of your suggestions? Kirbyworshipper named a few companies a few pages back (I'll edit this post with them after I find the message edit: Marvelous, Grasshoper, Natsume, Interplay, alongside some unnamed Indies), but I'd say SEGA could potentially push Arle or Kiryu as well (they have plenty of other franchises too but I'm not sure how big, recognizable or demanded they're in contrast, or if Sakurai has any particular bias to favor them lol, maybe Phantasy Star?).
As for Square...there's Crono, a Bravely rep, Octopath Traveler, someone from Nier, Lara Croft, maybe even the guy from Deus Ex? I think their next candidate (if they get anything else) is not as clear cut as Hero was before.
I take Spencers comment as a soft disconfirmation for these, but I guess MS could push Steve or MC still, maybe even another Rare rep like Fulgore or something, but I consider that among the unlikeliest of double dipping possibilities, only above SNK imo.
I'll also say I have a hard time taking a Touhou rep chances all that seriously when it feels like most of the series clout comes from fan projects and not official content, but that might be my ignorance on how the hell the IP is handled speaking. I admit I have a particular bias against the idea as it reminds me of someone I really can't stand.