dunkirk is almost certain to pass interstellar's dom number.....but I doubt oscar buzz will further drive people into watching dunkirk.
Using inception, that released in July too, being and oscar contender at the same time, didn't generate a single cent from oscar season in theater. Same may happen to dunkirk as it's already drop from theater.
Speaking of oscar, dunkirk oscar buzz instantly drop after its opening, even WW has more oscar buzz,I don't think there is any backlash but WB seem try to tame its oscar buzz to avoid any potential backlash against dunkirk. They would "reserve" the oscar buzz to later so that it keep fresh memories in oscar season I supposed