Though there are some strong suspicions that Ragnarok will be removed from the main MCU in a similar manner to Guardians Of The Galaxy, there is also a compelling theory that suggests that Loki's end-game in taking over Asgard is to continue impressing Thanos. And if that is the case, he needs to get the Infinity Stone he managed to carelessly lose ownership of to some two-bit Nazis. To do that, he needs to mount a serious arsenal - particularly as his superior brother stands in the way - and he rumour has it he will turn to Surtur the fire demon to do his bidding. Alternatively, he might summon the demon to help defend his new kingdom against Thanos (more of which later). Either way, Loki will bring the satan-like monster into the game. The Evidence The title of the film is very compelling evidence, since Loki's freeing of Surtur brings about Ragnarok and the destruction of the Norse Gods. And it's the kind of big deal that would certainly suit the storyline.
