Hossa, Kopecky, and Conklin are gone. Detroit isn't bringing back Samuelsson and Chelios. Hudler is a RFA, but there aren't any reports of teams making a counter offer. I'm sure Holland will try to get him to sign a new contract. Therefore, that will eat up some of the gap remaining under the cap.
According to
this, Detroit was involved in some capacity with trying to sign
Colton Orr.
There are a few 3rd/4thy line scrappers still remaining, like
Travis Moen.
Aaron Downey was invited to training camp 2 years ago, and made the cut. And he's still available. Who knows what will pan out as the summer rolls along.