I don't think Strange wanted to change the outcome. He said what happened is the only way.
Its unfortunate AoS is probably ending this season because if my theory is correct next season could have been really fun.
I believe Thanos wiped the people who dusted from existence and Avengers 4 will largely be a What If world where those people never existed. What effect would that have on SHIELD? If Nick Fury never existed SHIELD is a much different place.
AoS could have run an entire season in that What If world leading into Avengers 4. There could have been little hints something isn't right, maybe even introduce a character that knows the truth. It could have been glorious (if I'm right, and I'm 97% sure I am).