Originally Posted by BigThor
But it's been confirmed that Thanos is not a main character in GOTG, so he's not going to be the actual "threat".
I can pretty much guarantee that's not going to happen, espescially since Joss promised a smaller more personal story. Besides Ultron works better as a threat to mankind not a universal threat which is why he's traditionally depicted that way more often.
Nothing has been confirmed about Thanos, other than that he will have "much more than a turn around and smirk" role, and that depsite Ronan being the main villain, Thanos is there as a character, overshadowing the whole thing. may not have "the most screen time", but if anyone thinks that he won't have a MASSIVE presence in the movie, I think they are wrong.
As for Ultron, well Joss said more personal, in terms of characterization, but the scale of the movie is suppose to be huge, Joss said it's a globe wide film