By now Marvel has shown that their heroes will almost always come out on top, and better for having overcome their obstacles.
Had the Marvel cosmic universe seen its guardians removed after Age of Ultron, Thanos would have a cake walk.
And what this film does is it breaks them down in a very similar way [to how] Winter Soldier broke down S.H.I.E.L.D..
And with Thor on track to become King of Asgard, the Asgardian army could arguably render the Avengers overkill for even the most fearsome alien menaces.