Major spoilers for Thor: Ragnarok are in this story. Stop reading now if you haven't seen the movie.
Taika Waititi's Thor: Ragnarok is a pretty contained story in terms of the Marvel Cinematic Universe. Thor (Chris Hemsworth) is on a mission to remove his step-brother, Loki (Tom Hiddleston), from the throne. In the process, he's also trying to prevent Hela (Cate Blanchett), the Goddess of Death, from taking over Asgard. The movie answers a few larger MCU questions, but leaves on major question lingering, until now. Who's ship is that that appears in the mid-credits scene? Marvel President Kevin Feige finally reveals:
And there you have it. The name "Sanctuary" ties directly to Thanos, the Mad Titan. It was the domain of Thanos that we saw in the Guardians of the Galaxy scene where Ronan confronted the celestial beast.
In the comics, Sanctuary II was a massive ship that served as an Ark, so it makes sense that Marvel Studios would start to introduce Thanos (Josh Brolin) to the storyline, as we only have one other movie -- Black Panther -- before we land on Avengers: Infinity War, when all hell is supposed to break loose.
We broke down some of that information in our end-credits scene analysis, but Marvel President Kevin Feige confirms to The Wrap that it's The Sanctuary II, and now we know that Thanos will be on board. What I find interesting is that an "Ark" type ship arrives on the scene right when Thor has the entire body of surviving Asgardians in his possession. Will Thanos kidnap "Asgard," and will that be Thor's main motivation to fight?
Piecing together what we know from the Avengers: Infinity War trailer that was shown at D23 and San Diego Comic-Con, we can assume that Thaons makes quick work of Thor and Hulk, because when the Guardians of the Galaxy arrive on the scene, a beaten and bloodied Thor lands on their windshield. It's possible that the Infinity War movie opens with Thor and Hulk versus Thanos, but until we see that official trailer, we won't know for certain.
If I had to project out, I'd think that Ryan Coogler's Black Panther will act in a similar fashion. It will 99% be a self-contained Black Panther story, with a small tease at the very end for the massive Marvel team up that will arrive in its wake. So, until then, visit our Black Panther preview page for information, our Avengers: Infinity War page for information, and brush up on all Upcoming Marvel Movies here.