If we are getting a proper Indie rep, its either Shantae or Reimu. No other indie character has a chance I feel. Most other indie reps are 1 hit wonders and no 3rd party rep has been from a one hit wonder game, Quote is not happening because of all the drama and other things around him and the company. If Silksong actually has had any news withing the last 12 months I would say MAYBE Hornet was a likely choice as well.
Shantae series and the touhou series are the only 2 long time indies own franchises out there. Shantae's advantage's is wayfoward has a long history with nintendo, she is well known, and Nintendo has worked with Nintendo closely. Touhou's advantages are its the grandaddy of all doujin games, most developers know touhou and reference it, Reimu has been in a game with Kirby, touhou fan games are starting to appear on the switch outside of japan, and it is an understatment just how massive the series is to many indie/doujin creators in japan in not just video games but music, animation, and manga.
It is impossible to say which has the higher chance I feel, and I will not say who deserves the first playable indie spot more. I just am sad how much hate I see for touhou from some users in this thread, when I LOVE both series and characters so much. If either gets in, we should all be excited, because either are great indie reps, and indie developers deserve some top reconition from this game.