(Warning! THIS POST CONTAINS SPOILERS FOR AGE OF ULTRON)
So, we all know that Marvel's phase 3 is all set up and that phase Two was beautifully ended. And some scenes from Age of Ultron possibly Had huge hints for what's coming.
For example, when Tony Stark sees all the Avengers dead in a pile of bodies, we can see that there are some characters that haven 't been formally introduced in the M.C.U, until now, leading us to believe that what Tony saw was a glimpse from Avengers: Infinity Wars ( I mean, it's THANOS we are talking about!).
In Age of Ultron, we had four characters that where enchanted by Scarlet Wich: Iron Man, Cap, Thor and the Black Widow.
Of those four characters, two of them saw the past ( Cap and the Black Widow), while Iron Man and Thor saw the future. Wich leads me to believe that only Thor and Iron Man will survive until Phase 3 is over.
As for Thanos mid -credits scene, we can see that the Infinity Gauntlet doesn't have any of the Gems, so Thanos is going after the Gems himself, and IS GOING TO kill Vision to obtain the Mind Gem, probably in Infinity Wars: pt 1.