Watching the trailer and thinking about what could be the premise.
Maybe it could be this (comic references):
Maybe this is Ultron's origin is going to be. They appear to be setting up the Kree as some invasion force with those Ronan shots, so maybe the Kree are under assimilation from the Phalanx (Annihilation Conquest).
Then, when they purge the Phalanx from the Kree, it manifests into Ultron for the Avengers at Earth. I dunno, definitely seems like the Kree are the enemies in this movie.
That's quite a leap you've made. Literally none of that could be inferred from the two trailers. It's the Guardians versus Ronan/Nebula fighting over an Infinity Stone. Seems pretty transparent to me.
Ultron's origin is more likely stemming from stuff that happened in Captain America: The Winter Soldier, given that he's an Avenger villain first and Captain America is in an Avenger and they're both going to be in the next Avengers movie.