Aren't Avengers 4 reshoots happening right now?Two things.
First: Someone will almost certainly die in the next Avengers. It will likely be Steve or Tony (if not both). There doesn't need to be a large death count other than that.
Second: They already filmed Avengers 4. Doing reshoots to kill off the Guardians of the Galaxy is legitimately crazy and would be a disaster from a story and filming point of view.