Ariza could still take his name out of consideration by June 17th. The draft is June 24th.
Ariza, if he does keep his name in consideration past June 17th, but doesn't get drafted, could also still return to UCLA.
Sources, though, indicate that it's generally unlikely Ariza will return to UCLA, even if he does take his name out of consideration or keeps it in the draft and is not drafted. The word is that the Ariza camp intends for him to leave UCLA regardless, most likely to pursue any pro options available.