They still need someone if they want to compete with the iron in the league and make deep playoff runs. We had it for a while with Horford, Timelord (then Porzingis), and even Kornet as a consistent 3rd big. I think Amari can become the 3rd big in a year, but they need someone to pair with Queta.
Queta has made amazing strides so far this season but a game like yesterday highlights it's still a need.