The fifth character will either be a falsely deconfirmed character like Crash or Dante or a character everyone deemed impossible, "too niche", or "Inappropriate for the TGA's"
I wanna say it may be the former, though.
The few "viable" ones even left are Dragonborn, Reimu, Frogger?, Bill Rizer, Jonesy, Sora, or Kratos.
I may be remembering wrong, but I'm pretty sure Vergeben deconfirmed Capcom as a whole.
But if I'm misremembering, we could have Phoenix Wright, Amaterasu, or Monster Hunter.
And if third parties CAN double-dip in the same Fighter's Pass, then Square-Enix has Lara Croft, 2B, and Crono, and Microsoft has Steve and Master Chief. Sega has... Aiai from Super Monkey Ball?
And if Fighter 5 is another SNK character, I will pour vinegar into my belly button and drink it with a straw. I am that confident it ain't SNK.