Carl
Cheesehead
The safety position didn't improve because the Packers released Jennings. The reason was Thompson spending a first round pick on Clinton-Dix and moving Hyde (who played extensively as a rookie) to the position. Getting rid of Hawk and Jones and hoping some guys who have never played a single down at ILB will improve the position isn't a great strategy.
Shields was a rookie that season who proved from the start that he can start in the league. You can't compare the situation to any of the ILBs currently on the roster who weren't able to move ahead of Hawk and Jones on the depth chart last year.
The Packers didn't rely on any of the other guys you mentioned entering 2010. They were backups who got extensive playing time because of injuries.
With the draft still to come, I don't see how the Packers will be relying on guys who have never played ILB. An ILB or two will certainly be drafted.