I think this is a little bit of an overstatement on your part. I mean we lose Cullen as the only real player from last years roster. Barnett and Chillar didn't play enough to earn consideration. I agree our ILB backups are light, FA just started and I am sure if TT is not happy with Smith and whomever else, he will pick up a guy. I am really not worried about this.
Our DL loses one guy, our rookies from last year get another year to improve their abilities. Therefore we gain their increase in skills. Plus another year of improvement from Raji. I think our DL play will actually improve this year even with the loss of Jenkins.
Our OLB's improve as all of our young guys from last year have another year of increased skills/strength/speed. We add Elmore who led the PAC-10 in sacks and we get CM3 another year of improvement.
So realistically our front seven improves slightly, and I would be willing to say that TT does something if he is not happy with the ILB depth. Why overpay for a FA ILB right now when we can wait and let the prices come down on these FA's. Plus we will get to see whether Smith, Jackson, or Joseph can actually play.
I'm not saying you have to be optimistic but you are sounding too pessimistic right now.