They will probably just make Gohan's Ultimate form stronger than give him any new form. They kinda have to give Trunks something since Super Saiyan 2 wasn't going to cut it and giving him Super Saiyan 3 wasn't going to save him either. So I can understand why Toei gave him his own Super Saiyan form. If they didn't, he would be like Trunks in the Super manga who stands back and let daddy Vegeta and uncle Goku handle everything while he give commentary.
You know, manga Future Trunks is more useless than his Cell Games counterpart and Anime Vegeta would smacked Manga Trunks shit for sitting back and depending on others to fight.
PS: Sorry about the manga rant.