The Time Stone in Doctor Strange, so characters going forward and backward in time is certainly on the table for the blockbuster.
In the case of the latter, we already know time travel is possible thanks to the Eye of Agamotto a.k.a.
So that leaves us with the big question: why is Black Widow wearing that familiar costume?
In the case of the former, a non-linear narrative would make a certain degree of sense, given that the film is meant to be a capstone and reflection of every MCU title that came before it.