You may fight him as Johnny in a flashback but that outcome is predetermined as per the lore (Johnny gets buttraeped). Therefore there is absolutely no doubt that you will fight him again as a player near the endgame; with Johnny egging you on inside your stupid brain. He will likely have Johnny's gf as a hostage and you have to save her.
This game will revolve around fulfilling Johnny's agenda's. The only free agency you as a player will have will be driving around like a retard and shooting people in the street until the flying cops come and kill you, just like GTAs.
Enjoy your RPG of the Year morons. The
crowd will be playing Wrath of the Righteous, & Solasta instead. (and mayyybe BG III if it massively improves the writing over DoS series)