Avengers: Age Of Ultron Ending - 14 Implications For Phase 3 And Beyond

Given that Thanos' end-goal is to unite all of the Infinity Stones, or gems - or whatever you feel like calling them - the likelihood of Vision keeping his prized possession isn't exactly high.

He might be a considerable threat in himself (despite being knocked out by the stone's power in a face-off with Ultron at one point), but the narrative requires him to be defeated for Thanos to get his hands on the Mind Stone. And unless he's just going to stick around as a de-powered JARVIS android who can't fly, can't change his appearance and has limited powers beyond invulnerability, that probably spells death for him.

You'd probably like to think that the mid-point of Infinity Wars would see Thanos click his fingers and kill everyone spectacularly to build suspense, but it makes more sense that it would be him getting his hands on the last, most protected stone.