What they need more than anything are athletic guards that can play defense.
Love TJ, but he's an average athlete, so is Henderson and Nik is even more limited, Sergio is gone b/c he's a matador.
Get some guards to go along with TLC, and suddenly this becomes an elite defense.
RoCo and Saric can shoot, and Nik can shoot off the bench, while Henderson and Bayless are decent shooters as well.
So unless you can land a great shooter, you're looking at 2-3 years to find out whether you can teach an athlete to shoot (remember MCW?).
But defense can help from day 1.
Simmons will control the half court offense, so a PG just has to bring it up, he doesn't have to be a great distributor (TJ is pretty good in that role).
An SG/SF with a great 3 point shot would certainly help, especially off the bench, but it's not a huge priority.
This works to the Sixers' advantage, they can draft for upside and stash someone for a year to learn how to play and fill out.
TLC is a perfect example of this strategy, next year he hopefully can take a big jump as he gets stronger and improves the mechanics on his jumpshot.