HAKI:
No point in training Adv. CoA since his Sonic ability is already better than that
Mastering Adv. CoO would be fitting seen how good he already is with reactions/reflexes, he has a good shot at getting it
Being a R5, I don't exclude the possibility of him revealing CoC at some point
SMILE:
I still have the inner hope that he may awaken a form out of the failed SMILE, either Kamaitachi or Fenrir
STREETSMARTS:
Don't forget that brain is one of Killer's sharpest weapons, Oda went out of his way to show it
I expect this to be a constant in Killer's fights