Kurt coleman started many games last year at strong safety and played a significant amount of snaps. nate allen was the openeing day starter at free safety and had 3 picks in the first four games before he got injured so i'm not really worried about safety. plus when you have 4 stud corners, who cares? linebackers are slightly a concern but we picked up better defensive tackles for our new scheme....again not worried.
what happens if any starting qb in the nfl gets injured? yeah, we'll likely be a worse team as i'm sure the giants would be if manning breaks his leg.
but to answer your question, if vick pops a hammy we'll go with kafka....young is in philly to rehab his image and get quality qb coaching. he's merely trade bait for the next offseason. eagles will land another 2nd round draft pick for a backup qb just they did with aj feely and kevin kolb