Well and that's the point--everyone has lingering injuries, and playing late into your career with a deteriorating body is risky for anyone. Knowing that everyone has those issues, it's going to be a tough sell to the league when Player X, who happens to carry a cap-crushing hit, is suddenly deemed by a team's physician to be no longer capable of playing. That's probably going to raise some red flags in the League's office.
Anyway, LTIR is for players "unfit to play (i.e., is injured, ill or disabled and unable to perform his duties as a hockey Player)." It's not really for guys that are banged up who have creaky knees that might fall apart if they keep playing. For those guys? It's retirement. Chris Pronger, for example, is able to sit on LTIR forever because he's still suffering debilitating daily effects of PCS. If he became "healthy," though--that is healthy enough to return to his duties--he'd have to come off LTIR or retire. Simply being "at risk for further injury" isn't grounds for being placed on LTIR; you have to actually be physically unable to play.
If a guy is actually injured and unable to play, yeah, he could do LTIR. But again, when healthy, he'd have to come off or retire. Being old doesn't qualify a guy for that list.
