@zoniax2: I think Dr. Strange gave up the time stone specifically to save Tony, because Tony will make the ultimate sacrifice in the end. I think Tony bites the bullet in the next movie.
@cmac14: Dr. Strange obviously gave up the time stone on purpose, because having Stark alive somehow plays into the one scenario he saw where they could win against Thanos. There is no other reason why he would have given up the stone just to save one single life.
And when Tony asked him why he did that, his final words were a big giveaway, "This was the only way".
However it plays out with them getting the gauntlet from Thanos and using the time stone to undo the damage, I think Tony makes the ultimate sacrifice in the next movie.
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