Set to mark the beginning of the end of the MCU's first three phases, it is expected that Avengers: Infinity War will be a huge movie, one that will see heroes and villains fighting throughout the entire known universe. Given Thanos' quest to gather all of the Infinity Stones, we can expect him to visit Asgard, Xandar, and the Collector (wherever he may be right now, after the events of the first Guardians of the Galaxy movie).
But, according to Comic Book, these won't be the only places and planets we’ll see in the movie - in fact, these are just a few of them:
Any time you turn that page on this script, you're kind of staggered, blown away, terrified by what's in front of you. I think rather like Doctor Strange, you'll find this film, it's not regurgitative, yeah? What I'm trying to say, is, there are many, many, many new worlds to see in this film.
Where could we see the Mad Titan and, presumably, his enemies? It’s anybody's guess. However, we do know where he will end up: back on Earth, where there are at least two Infinity Stones: the Mind Stone (on Vision's forehead) and the Time Stone (revealed to be the Eye of Agamotto). And here, most likely in the still-untitled Avengers 4, we will see Thanos' quest come to an end.
But, according to Screen Rant, we may know of yet another location where Thanos might go – to Nidavellir, the planet of Eitri. As it was recently revealed, Game of Thrones' Peter Dinklage is in talks for a role in the next two Avengers flicks. And while we assumed that he would sign for the role of Pip the Troll (given the character's role after the Infinity War from the comics), the website mentioned above believes that the actor might play Eitri, the King of Dwarves.
And this is also an important character, since he forged numerous legendary weapons (in the comics, at least), including Thor's Mjolnir and a very powerful Iron Man suit for Tony Stark. So, in flashbacks or otherwise, he could be established as the creator of the Infinity Gauntlet, and the one who could find its flaws.