This article contains SPOILERS for the ending of Game of Thrones.
Game of Thrones might be over, but HBO is going to be milking that cash cow with spinoff series for as long as people are interested in watching. Whether as many people are still as interested in these spin-offs after the show's final season is an open question. The last six episodes of the series have been a mixed bag, to say the least. While the series finale wasn't the disaster it could have been, any future spinoffs will have to be a lot more than "not a disaster" to make a return to Westeros enticing for millions of viewers disappointed in GoT.
Four potential sequel hooks are built into the final episode. There could be a West Wing-style political drama about Tyrion and the rest of Bran's counsel rebuilding Westeros in peacetime. Sansa's queenship over The North has storytelling possibilities that would probably be the closest thing to a proper "Game of Thrones Season 9" tonally. Jon Snow's out with the Night's Watch again, and while Jon probably had the most underwhelming role in the finale, maybe someone at HBO thinks there's potential in exploring the many underdeveloped and unexplained aspects of his character.
The one sequel hook with the greatest potential, despite HBO programming president Casey Bloys saying there are no plans to explore the future, is one that explores Arya's path. Consistently one of the most interesting characters in the series, Arya's defeat of the Night King was easily the best part of Season 8. Now, having failed to kill Cersei and encouraged to find purpose in life beyond revenge, Arya's decided to become an explorer. At the end of the final episode, she's set sail to find out what's West of Westeros.
"West of Westeros" (that title has a good ring to it) would be an ideal follow-up to Game of Thrones. It would promise something distinct from the old series, with a new story and a completely fresh setting to explore, while expanding George R.R. Martin's mythology and giving viewers more time with a character we know and love.
Now, there is a way this concept could go all wrong. While some cheered for Arya heading out on her new voyage, other reactions have been more concerned. "Oh no, she's gonna be a conquistador!" is the main worry. Given Westeros is basically a fantasy version of Europe, and Essos is a fantasy version of Asia, it's safe to assume whatever new land Arya finds in the West is gonna be a fantasy version of the Americas. If, for example, HBO's crafted an "explorer" narrative set in a fantasy America, it's gonna have to be able to deal carefully with Native American cultures and the ugly history of European conquest.
Game of Thrones has never earned praise for a particularly sensitive handling of racial issues. It's a predominantly white show, and the treatment of its characters of color has often been criticized. While Daenerys' arc was a well-meaning attempt at critiquing colonialism and "white savior" narratives, the execution of that arc lacked clarity or proper development. There's a reason everyone groaned about David Benioff and D.B. Weiss proposing Confederate, a "What if the South won the Civil War?" alternate history as a potential project.
Benioff and Weiss, however, are done with Martin's world for now, focusing their energies on their new Star Wars trilogy. The different spinoff series will have different creative teams (Jane Goldman is running the first spinoff, a prequel about the origin of the White Walkers). Get a great new showrunner and a diverse group of writers onboard for the "West of Westeros" spinoff and the potential is limitless.
Perhaps Arya ends up more like a Leif Erikson figure rather than a Columbus, exploring a new land without conquering or enslaving it. Perhaps the show takes full advantage of its fantasy nature to imagine a new history of the Americas without European imperialism even becoming a thing.
If it does want to deal with imperialism, there are many worthwhile ways it can explore that too. Perhaps Arya's peaceful forays lead to other more violent voyages from others in Westeros. Maybe there are other explorers/conquerers already in this new land, but from Essos rather than Westeros, playing off how the Chinese discovered America before the Europeans did.
With particularly smart writers, even the feared "Arya's a conquistador" plot could be the sort of uncomfortable but insightful villain protagonist story that Daenerys' story failed at being. Just make sure HBO actually has some Native Americans in the writers' room to keep it from becoming tasteless.
Game of Thrones might have ended on some disappointing notes, but that ending has laid the groundwork for what could be an incredible Arya-centric spinoff.