Dragon Ball 'sSuper underlying premise has been all about the series' heroic Saiyan duo (Goku and Vegeta) surpassing the limits of mortal warriors and tapping into divine powers that have given rise to forms like Super Saiyan God, Super Saiyan Blue, and beyond. Dragon Ball Super's big culminating anime event was the Tournament of Power, which saw Goku achieve a new state known as Ultra Instinct - a divine power so great that even the gods themselves are envious a mortal has manifested it. Goku is currently trying to master Ultra Instinct's power (his greatest challenge yet), but when he does, it's inevitably going to force Dragon Ball to evolve as a series.
Right now, while Dragon Ball Super's anime is on hiatus, the manga has begun moving past the Tournament of Power into a new storyline that sees Goku having to train with a mysterious new teacher (Merus) who possesses the divine knowledge of how to properly master Ultra Instinct. He's now taken Goku in a Hyperbolic Time Chamber for a life-or-death training regiment that will supposedly re-awaken Goku's Ultra Instinct abilities in full. The manga isn't the only place that storyline is being explored: the Dragon Ball Heroes promo anime has taken Goku under the wing of Grand Priest, in order to reach a new level of Ultra Instinct control that will allow the Saiyan warrior to defeat a new team of villains terrorizing the multiverse. However it ends up happening in the official anime canon, it seems inevitable that Dragon Ball Super's next anime installment will have to deal with Goku's challenge of mastering the technique, sooner before later.
...But then what?
We've already pointed out in our feature on what Dragon Ball spinoffs should be added to the series that once Goku fully masters Ultra Instinct, he'll arguably be beyond the power of the gods of his universe. Dragon Ball has already lost so much momentum with its cast of Dragon Ball Z supporting characters (Gohan, Piccolo, the other Z-Fighters) as Goku and Vegeta got so overpowered during Super - once Goku reaches the Ultra Instinct mastery, he will will be in a whole other league of Dragon Ball battles which the other characters won't fit into at all. The manga has acknowledged that even Vegeta can't keep on just being the warrior who tags along behind Goku's achievements; the Prince of Saiyans has decreed he will never again relay on Goku's power to save the day, and split off on his own journey to achieve a new power-up. So once Goku reaches the true potential of Ultra Instinct, it seems that achievement won't be used as the next bar Vegeta must then reach - since the ToP, it seems Dragon Ball truly intends to make Goku and Vegeta into different types of warriors.
Which brings us back to the point: In mastering Ultra Instinct, Goku will become a godly figure of the Dragon Ball universe. It's hard to imagine how the main series continues as it has been after that, as a godly Goku would probably be better served heading up his own series (or becoming just a recurring figure in the main series), while the man Dragon Ball Super story continues with the other characters having to step up to the challenged of filling in for Goku's absence. Anything else (like Ultra Instinct just becoming the new standard for all the main Saiyan characters; or the technique once again mysteriously disappearing, even after it's "mastered") would just feel like a major cop-out.
Dragon Ball Super currently airs its English dub on Adult Swim during the Toonami programming block on Saturday evenings, and is also available to stream on Funimation and Amazon Video. The Japanese-language release of the series is complete, and available to stream on FunimationNOW and Crunchyroll. The manga has chapters that can currently be read for free thanks to Viz Media, and Dragon Ball Super's big movie, Dragon Ball Super: Broly, is now available on Blu-ray and DVD.