^Daredevil reboot, apparently.
FOX still owns the movie rights to Daredevil. If want their original choice director back, they can postpone Daredevil to put Slade back on Wolverine.
It probably would have been best not to ask Aronofsky in the first place. The guy ends up leaving every superhero movie he is rumored/reported to be involved in: Batman: Year One, Robocop, Superman and Wolverine.