Earlier this year, it was rumored that when we reunite with Clint Barton in Avengers 4, he will be in a “very dark place” following the events of Avengers: Infinity War.
No specific details were provided for this identity shift (I suspect something tragic will happen to his family), but assuming this information is true, then it means that at least for the beginning of Avengers 4, he won’t be wearing anything close to what he’s worn in his previous Avengers operations.
However, assuming that Jeremy Renner’s post is from the Avengers 4 production, those arrows on his back mean that eventually he’ll revert back to a more classic costume, complete with his traditional weaponry.
As a result, not only will be he showing off a different haircut, but he’ll also be garbed as Ronin, the identity he took on temporarily in the comics following the Civil War conflict.