VEGETA AND TRUNKS ARE GOING TO USE THE POTARA RINGS TO FUSE INSTEAD OF GOKU! Here's why;
In the earlier parts of this arc, Goku Black terrorized Trunk's and the remaining survivors to the point where Trunks has PTSD. Black killed Future Bulma, and Trunks constantly relives that moment. For him to find resolve, he would need to defeat Zamas. This is similar to how Trunks resolved the death of Future Gohan when he got back to his timeline and killed the androids. Defeating Zamas would complete Trunk's characterization for this arc.
Back in episode 54 of DBS, Trunks and Vegeta had a sparring match where Trunks was given the challenge of landing one hit on Vegeta. Trunks ends up getting blown the **** back and loses the match followed by Vegeta saying "You fool!...Is defeating Black your only goal?! Look further ahead at the enemies you've yet to face...the universe's strongest!...If you are my son, I will not allow you to lose to anyone" . Trunks then headbutts Vegeta, completing his father's challenge and proceeds to say, "I will surpass both Black and you". This not only foreshadowed Trunks' power boost in the more recent episode, but also the fact that Vegeta will be the one to help Trunks defeat Black.
3. This Arc has been more about Vegeta than it is Goku;
For the majority of Super Goku has been on the forefront, facing all the main villains and gaining new forms while Vegeta is constantly standing on the sidelines, but during this Arc Vegeta's been on the front lines taking on Goku Black. Vegeta lost his first fight with Black after Black went SSJ Rose for the first time. After that, defeating Black became personal for Vegeta. We even see it in the latest episode (64), where he faced Black again. It's gotten to the point where I've noticed how much this arc revolves around Vegeta, combine that all the inner monologues Vegeta had back when he watched Goku and Berus fight, and you come to the conclusion that Vegeta will be the one to resolve this arc.
In episode 61 Trunks got a new unnamed transformation that looks likes like regular super saiyan but surrounded with blue god ki. We don't know if he's as strong as Goku or Vegeta in SSJ blue, but he was strong enough to take on Black in SSJ rose which puts him on par with Vegeta, who can also take on Black in SSJ Rose. Them being on the same power level makes them fusing with the potara's more plausible. In the DB wiki it says "If two non-equal beings combined, the superior one will be in control...In the case of two equal beings, the fusion will form an entirely new being with a personality traits of both fusees. ". It was intentional to show that both Trunks and Vegeta were able to overpower Black, so we know that they're equal in power and would be able to fuse with potara rings.
Trunks and Vegeta already have a fusion transformation in game, that only recently came out in terms Dragon Ball super. I don't think that Vegeks will directly make his way into DBS, but I do believe it was hinting at a transformation between Vegeta and Trunks. I doubt the fusion name will be Vegeks, or that he'll have the same hair style, but I do believe we'll see them fuse in the anime and manga. This is the weakest reason, but this only supports the idea that Trunks and Vegeta may fuse.
1. Trunks beating Zamas/Goku Black is personal;
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In the earlier parts of this arc, Goku Black terrorized Trunk's and the remaining survivors to the point where Trunks has PTSD. Black killed Future Bulma, and Trunks constantly relives that moment. For him to find resolve, he would need to defeat Zamas. This is similar to how Trunks resolved the death of Future Gohan when he got back to his timeline and killed the androids. Defeating Zamas would complete Trunk's characterization for this arc.
2. There have been foreshadowing of Trunks beating Goku Black;
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Back in episode 54 of DBS, Trunks and Vegeta had a sparring match where Trunks was given the challenge of landing one hit on Vegeta. Trunks ends up getting blown the **** back and loses the match followed by Vegeta saying "You fool!...Is defeating Black your only goal?! Look further ahead at the enemies you've yet to face...the universe's strongest!...If you are my son, I will not allow you to lose to anyone" . Trunks then headbutts Vegeta, completing his father's challenge and proceeds to say, "I will surpass both Black and you". This not only foreshadowed Trunks' power boost in the more recent episode, but also the fact that Vegeta will be the one to help Trunks defeat Black.
3. This Arc has been more about Vegeta than it is Goku;
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For the majority of Super Goku has been on the forefront, facing all the main villains and gaining new forms while Vegeta is constantly standing on the sidelines, but during this Arc Vegeta's been on the front lines taking on Goku Black. Vegeta lost his first fight with Black after Black went SSJ Rose for the first time. After that, defeating Black became personal for Vegeta. We even see it in the latest episode (64), where he faced Black again. It's gotten to the point where I've noticed how much this arc revolves around Vegeta, combine that all the inner monologues Vegeta had back when he watched Goku and Berus fight, and you come to the conclusion that Vegeta will be the one to resolve this arc.
4. Trunks' new power up;
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In episode 61 Trunks got a new unnamed transformation that looks likes like regular super saiyan but surrounded with blue god ki. We don't know if he's as strong as Goku or Vegeta in SSJ blue, but he was strong enough to take on Black in SSJ rose which puts him on par with Vegeta, who can also take on Black in SSJ Rose. Them being on the same power level makes them fusing with the potara's more plausible. In the DB wiki it says "If two non-equal beings combined, the superior one will be in control...In the case of two equal beings, the fusion will form an entirely new being with a personality traits of both fusees. ". It was intentional to show that both Trunks and Vegeta were able to overpower Black, so we know that they're equal in power and would be able to fuse with potara rings.
5. It was teased in Xenoverse;
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Trunks and Vegeta already have a fusion transformation in game, that only recently came out in terms Dragon Ball super. I don't think that Vegeks will directly make his way into DBS, but I do believe it was hinting at a transformation between Vegeta and Trunks. I doubt the fusion name will be Vegeks, or that he'll have the same hair style, but I do believe we'll see them fuse in the anime and manga. This is the weakest reason, but this only supports the idea that Trunks and Vegeta may fuse.
