It was revealed at this past San Diego Comic-Con that Captain Marvel will take place in the 1990s, approximately a decade (or more) before the modern MCU era.
Because Captain Marvel takes place at least 20 years before what goes down in Avengers 4, the big question is where has Carol been for all these years?
Carol’s energy powers will also be most handy against whatever threat the other MCU heroes are dealing with, be it Thanos again or someone else.
If she does indeed appear in Avengers 4, then we’ll finally have that answer, as well as learn how she still looks the same after all these decades.