So something that has occurred to me lately, is that all newcomers hail from the same few companies.
Snake, Simon, Richter* - Konami
Megaman, Ryu, Ken* - Capcom
Sonic, Bayonetta, Joker - Sega
Cloud, Hero, Sephiroth, - Square
Banjo, Steve - Microsoft
Pacman - Namco
Terry - SNK
Before Terry was introduced, only characters from the same 6 companies were chosen, a trend that continued after Terry as well. I think a large part to why Terry was chosen in the first place was to be a rep for a company that didn't already have a playable fighter in the game, and I think the next DLC is going to fit that slot as well
So I'm wondering who would be an appropriate fighter from a company not already in the game? I think Ryu Hayabuusa and Crash Bandicoot would likely be the two best choices as far as I can see.