Well, you can't really get any more definitive than this, right? As there's an Infinity Gauntlet in Asgard, chances are that The Avengers and Thanos will be racing to assemble the Infinity Stones in order to wield its epic power. However, it would be hugely unsatisfying if we don't get to see Thanos unleash its full abilities at least once, and what better victim than Earth? If some of The Avengers were on his ship while the others were fighting down on the ground, it would create a huge amount of drama to have most of the team wiped out as Thanos - with a click of his fingers - blows the planet to smithereens. This could then lead to a ragtag group of Avengers being assembled in the second movie (just imagine a team made up of Iron Man, Spider-Man, Star-Lord, Black Panther, Captain Marvel, and Rocket Raccoon for example), and moviegoers would be left positively perplexed as to what the heroes are going to do now that their home planet has been completely decimated Alderaan style. As I mentioned before though, the Gauntlet could be used to undo all of this. Yes, that would lessen the impact in the end, but the weapon is a MacGuffin, and it would still make the initial shock of this happening no less great!
