Corners and safeties will be fine.
With the DT spot, I really like the talent in the underclass....especially when you add Mustipher and Hawkins to the mix. I don't think there's much dropoff when you have to lean on the likes of Givens, Jordan, Shelton, Windsor to pick up the slack of losing Cothren and Cothran.
Having said this, the real issue with the DL this year has not been the beef eating run stoppers, or lack thereof. It's been all about the absence of pass rush. In this respect, the DL will be GREATLY aided by the DE position being healthy with Brown and Buccholz back and having another year under the belt of Miller, Simmons, Toney and Matos.
LB will be the wildcard on the defense, but mostly center around replacing Cabinda since the unit does return Brown, Farmer (assuming he's back for his last year of eligibility) and Bowen (assuming he's out of the doghouse) for the outside.
All things considered, I'd just point to that middle LB position as having the biggest vulnerability going into next year...and probably the only position there's a real noticeable dropoff in week 1.