Dragon Ball Super, the latest canonical series in Akira Toriyama's beloved manga/anime franchise, introduced the Gods of Destruction. Each reality in the Dragon Ball Multiverse has its own corresponding deity filling this role, with Beerus as the God of Destruction for the franchise's main world of Universe 7. Initially introduced as an antagonist, Beerus eventually became Goku and Vegeta's martial arts trainer along with his companion Whis. However, by the end of Super, this appears poised to change, as Goku breaks through his physical limits once again, tilting the odds of his inevitable rematch with Beerus in his favor.
After harnessing the power of a Super Saiyan God, Goku put up a surprising effective fight against Beerus, forcing the God of Destruction to tap into his full potential to overcome him. After their bout, Goku would continually grow stronger, able to blend his new godly combat power with that of his Super Saiyan transformation resulting in the creation of the Super Saiyan Blue form. After mastering this form, Goku continued to train to surpass Beerus, combining his new transformation with the Kaio-ken technique to multiply his strength with this specifically in mind to Beerus' annoyance.
Goku and Beerus had never been seen in an active rematch since their epic confrontation after Goku first achieved Super Saiyan God. With Super Saiyan Blue and the Kaio-ken technique now combined, Goku has closed the power gap between the two considerably. While observing Goku battle from the sidelines, Beerus had grown visibly more uneasy, realizing his rival and pupil stood the chance was nearing equal footing with him. Even Goku observed that both Jiren, during the climactic Tournament of Power in Super, and Broly, in the canonical anime film Dragon Ball Super: Broly, were likely stronger than Universe 7's God of Destruction.
However, the Tournament of Power has completely redefined Goku's combat strength, with a significantly more powerful transformation revealed by the martial arts competition's end. Dubbed Autonomous Ultra Instinct by Beerus and Whis, Goku unlocked the form after absorbing the energy from a failed Super Spirit Bomb. Following this, whenever Goku pushed himself far beyond his natural limits in combat, he would tap into Ultra Instinct. As Goku maintained the mastered form against Jiren for a prolonged period of time, Whis indicated that the Super Saiyan God could control the godly combat state noticeably longer than Beerus.
While Goku has only been able to achieve the form since in the manga continuation of Super, the potential for Ultra Instinct means that Goku may have power roughly comparable to Whis. It was revealed that the various angels within the Dragon Ball Multiverse are actually far stronger than the Gods of Destruction that they accompany. With that in mind, Goku could have already surpassed Beerus and, if he can maintain the Ultra Instinct transformation without it taking a toll on his body, Goku could emerge triumphant in a long-awaited rematch.
Because of Beerus' temperamental nature and vast physical superiority, Goku has always deferred to the God of Destruction while steadily been training all throughout Dragon Ball Super to surpass him. With that in mind, Goku may have already passed Beerus completely by accident, an unexpected side effect of his battle against Universe 11's Jiren. And while a rematch against Beerus is likely in the cards at some point in the franchise's future, Goku may find an even more equal match in Whis!