What if Thor's phase 4 story arc ends with him leading The Avengers in the wake of Captain America and Iron Man's departures from the MCU? The Asgardian hero is only partway through his story arc, despite the revelation in Avengers: Endgame that Thor was still worthy (thanks to his meeting with Frigga in the past) and while he's currently heading to space with the Guardians Of The Galaxy, it makes more sense for him to return to Earth.
In the MCU so far, Thor has struggled with the weight of his father's legacy from his debut in Thor right through to Endgame and intriguingly, despite his birthright, he has barely been on Asgard's throne. From the moment Odin challenged Thor's attitude in that first Asgardian MCU movie, Thor has wrestled with the issue of worthiness, losing his powers and Mjolnir, losing Asgard, and finally losing his people, before his failure to defeat Thanos broke him. The cumulative effect led to him punishing himself as his PTSD manifested in excessive eating and drinking as Thor seemingly sought some control in his life.
The key thing for Thor heading into Phase 4 is that he still has lots of his story to tell. Asgard has settled on Earth, but there's been no exploration of what that means for the Asgardians or for Earth, Thor 4 will challenge Odinson's idea of what it means to be the God of Thunder (thanks to an interloper) and Thor has even said himself that he needs to explore who he is. With the rest of his arc and his past in mind, that should lead him back to The Avengers.
Thor Is Still Seeking His Place In The MCU
Had Guardians Of The Galaxy Vol 3 been released when it was intended to, it may be that MCU fans would have seen an entirely different story for Thor, but it's likely that Phase 4 will still do as Thor promised it would at the end of Endgame. After handing over Asgard's throne to Valkyrie, Thor headed off to space with the Guardians Of The Galaxy vowing to find out who he really is, suggesting that he's drawing a line under the MCU era that tied his existence entirely to Asgard's leadership. That much makes sense, because Thor's story has so far been told chiefly in of his relationship to other characters (Loki, Odin, Hela predominantly), other items (Asgard's throne, Mjolnir and the Infinity Stones) and he's never found himself. As much as that sounds like he's heading off for a gap year, it's not a bad parallel to make.
Crucially, Thor has never quite felt like an Avenger in the same way as the other original Avengers team . He was, after all, never an official recruit in the same way and his instinct when he was warned about Thanos' quest for the Infinity Stones was to go off alone to search for them. Yes, he was referred to as an Avenger, but extrapolating that to Earth's mightiest heroes and protectors doesn't quite ring true for the God of Thunder. Hopefully, Phase 4 will spend some time exploring what being part of that team actually meant to Thor, particularly when he's introduced properly to an entirely different team dynamic.
The Avengers Must Reform In Phase 4 Properly
While Phase 4 has no Avengers movie, it is only a matter of time before the MCU reverts back to its traditional phased approach to story-telling that builds up individual movies to one culminating event. Given the fact that the Avengers brand basically guarantees Marvel Studios and Disney a billion-dollar hit, there is no way fans have seen the last of the most successful superhero ensemble in movies. Having lost the original Captain America and the box office pulling power of Iron Man movies, there is no way a new era for the MCU would overlook the Avengers brand. It's simply illogical.
Already there have been major hints at what the next story event could be to replace Doctor Strange has the multiverse, Black Panther has Wakanda to rule and they need a reason beyond a villain to come back for it to ring true. The answer is for them to build on Endgame's message of unity and to have Thor reunite them once more.
Why Thor Is The Best Advocate For The Avengers
To understand the shape of Thor's arc into Phase 4, you have to look back to the end of Infinity War and the mistake that led Thor to become Fat Thor. Though Thor believed that that mistake was not aiming for Thanos' head, the reality is that the lesson he missed was a far more fundamental one and it began in the wake of Avengers: Age Of Ultron. When Thor was gifted the vision of Ragnarok by Scarlet Witch in Age Of Ultron, his response was to embark on a solo mission to find the Infinity Stones alone. That much was foreshadowed earlier in the same film around Thor's arrogance when faced with the possibility of his fellow Avengers lifting Mjolnir and even when Wanda manipulated his mind. In both cases, Thor was blinkered by the idea that he is the mightiest hero of all and the very suggestion of any weakness or even an equal in strength is inconceivable. That's why he ultimately chooses to seek the Stones alone and why he decides he's the one who must strike the killing blow on Thanos.
In Avengers: Endgame, Thor is faced with the crisis not that he is unworthy, but that he is fallible. His failure to find the Stones prior to Thor: Ragnarok is compounded by his failure to deal with Thanos even when he has a weapon made specifically for the task. No longer firm in the belief of his own power, Thor attempts to destroy his body and removes himself from heroism, hiding in Asgard as a glorified hermit. It's only when he comes back to the Avengers as a team that he is restored somewhat (thanks also to the reminder from Frigga that he is worthy). But then Thor misreads the lesson and leaves, seeking a team to be a part of (naturally assuming himself to be the new leader) in the absence of a true Avengers team and ing the Guardians Of The Galaxy.
The logical endgame of this arc is that Thor will learn exactly the same lesson Rocket learned in Guardians Of The Galaxy Vol 2, that teamwork and family are the keys. When he returns to Earth in Phase 4, Thor can advocate for the reformation of a real Avengers team to mark his own personal growth from a hero inclined to take things on alone (including his emotional baggage). He is the most informed to make that case and to bring together each of the individual heroes and it follows that he would be the best hero to lead them at first, satisfying the question of whether or not he was ever good enough.
