Theory-Bakugou's hero name will be "Kacchan"

When his character development has gone full-circle, he will accept "Kacchan" as his hero name the same way Izuku accepted "Deku" as his.

Unlikely, Kacchan sounds too cute for Bakugou to accept it as a hero name (although he doesn't mind being called Kacchan, he has been shown to prefer more violent names, which unless he starts liking cute stuff more, won't really change.) Deku actually has meaning to it that would apply to heroism (never giving up) while Kacchan is just a nickname.

Alternately, his official hero name will be Ground Zero, but Deku calls him "Kacchan" in an interview or something, and it will catch on so badly nobody actually calls him Ground Zero.

This comes from a post I read on Tumblr actually. And it does make sense, Izuku is a Magnetic Hero that his classmates change and found a new peace and hope for the future and the points the post make actually brought some light to what if no one acted right then in several turning points of Izuku's life. And with some fridge brilliance in mind, it goes a long way. Green, Izuku's color, is often associated to traffic lights that gives you a sign that you can now move forward and, in several RPG'fs, healing effects are cast as green, and gives some chance that you can survive more hits to go on with the game. And to go further, in heraldry, green can mean hope and growth.