These are thoughtful posts, and here is my two cents:
I wouldn't be quite so doomy-and-gloomy. The article that Bleacher Report put up about how Nebraska is going to be the most improved team in 2016 in the B1G points out that we actually had the stats of a 7-5 team last year, maybe even an 8-4 team, rather than a 5-7 one. It really was a snakebitten season. So, my point is, Im expecting an 8-4 or better season next year (I only see one game, possibly two, tOSU and Oregon, on our schedule that say "Loss") and that will allow the recruiting momentum to keep chugging along nicely.
Now, as to DT and the specifics there, I'm going to start by talking about the defensive line overall, then specifically DT. First, I think the starters and backups are going to be a LOT better than I was first fearing, but the one doom-and-gloom part I do completely agree with is, the drop-off after the backups is tremendous so we just cannot have any catastrophic inurjuries. We have basically 5 DT's to rotate between (posters here have said ideally you want 6), and we actually should be good on DE. I think Daishon Neal should see a lot of looks (6'7" and freaking 270? YEAH!), and I think Freedom is going to have a great season. Also, we get two nice tune-up games against weak teams to get the guys a little experience to work with. So, I see plenty of reason for optimism.
The other thing I would point out is, issues on the D-line aside, our linebackers? They're SOLID at LB this year for ONCE. I would not be surprised if over-production by the linebackers bails out the D-line a bit. Conference play is going to be against teams that love to run, so that actually tips in our favor a little.