To be honest, no Duke season will be as brutal as this past season, given the expectations.
I believe if Grayson returns, and we land Duval (he's a must, Knox would be nice too obviously) than next years team should be coming in with expectations similar to the 2015 team.
Duval = Tyus
Grayson = Quinn
Knox = Justise (probably the worst comparison of the group)
Carter + Bolden = Jahlil + Amile
This is without factoring in Frank, who should be one of the better players in the ACC.
In no way am I saying that next years team will be as good as the 2015 team, however the 2015 team did not come into the season as a juggernaut.