Dragon Ball Super teased another new transformation, but this one wouldn't be for Goku; instead, it could be discovered by Gohan. In Dragon Ball Super, it’s revealed that Goku’s son is continuing down the path that the Buu Saga put him on, with the character slacking off on his training in order to focus more on his personal life.
In preparation for the Tournament of Power, Gohan tried to become strong again, knowing that his power would be needed for Goku’s team to get a victory. With help from Piccolo, Gohan regained his Ultimate form and became stronger than ever. He even attained enough power to go against Super Saiyan Blue Goku. However, Gohan’s Dragon Ball Super story didn’t involve a new transformation. Goku and Vegeta, on the other hand, were able to achieve new forms. Goku discovered Super Saiyan God, Super Saiyan Blue, and Ultra Instinct, which is thus far the anime’s most powerful state. The series also introduced Super Saiyan Rage and Super Saiyan Blue Evolved via Future Trunks and Vegeta respectively.
Gohan could get a new form of his own in the next installment in the anime, which was made a possibility during Gohan’s fight with Goku. After noticing that Gohan wasn’t going Super Saiyan, Goku asked him why he wasn’t transforming. This prompted Gohan to say, “No, I have a new goal now: an ultimate form that no Saiyan has achieved before. And I'm going to pursue this form by going down a different path.”
For now, Gohan is staying in his Ultimate form, but there’s no telling how long that will last. Thanks to his diligent training with Piccolo, Gohan has evolved into Dragon Ball’s third strongest hero. Considering that he used to be above Goku and Vegeta, it may be too late for him to ever surpass them again, but his performance against fighters like Universe 11’s Dyspo proves that Gohan has made a great deal of progress. Also, the manga continuation has revealed that he and Piccolo continued to train after the tournament, which means that he won’t be slowing down anytime soon.
What exactly this new form will be is a question that Dragon Ball Super doesn’t provide an answer for, but Gohan’s words to Goku do indicate that it will involve a divergence from the Super Saiyan path. Similar to what Goku did when he unlocked Ultra Instinct, Gohan could discover a completely separate transformation. It’s unclear for the time being if it will be exclusive to Saiyans, or something that any being can attain. As for how powerful it’ll be, it’s likely that it’ll further the gap between him and the other Z-Warriors. It’s believed that Android 17 is quite close to him in strength, but that may not be true anymore after Gohan transforms. Also, it could be that Gohan’s new form will put him in the same league as Goku and Vegeta. If so, he could play a much more prominent role in the next Dragon Ball saga.