I'm not worried because every year we hear about how Glenn will not make it through the season, but with the exception of one year, he has played in practically every game since he has been a Cowboy. Glenn doesn't get enough credit for how tough he is or what a gamer he is. He is fast, runs great routes, has great hands and can take a hit as well as anybody. The idea that he is more injury prone than anybody else is a misperception.
All of that being said, we can ill-afford to lose him. The blessing in disguise is that we get to see what guys like Hurd, Austin, Richardson, Rector, etc. can do while TG gets his rest. He will probably be given lots of rest throughout the season anyway.