Who was it that said there's not much of a market for Lehtonen?
One post above ... Freidman.
Reading between the lines, Dallas isn't willing to retain salary or take a bad contract back. If they were, you can trade just about anyone.
I'm OK with taking that stand assuming you don't sign another backup goalie. Give Kari every opportunity to bounce back, but you've got either sign (will be tough) or trade for a guy that can truly push Kari.
I say it will be tough to sign a guy because where would you rather sign between Dallas, Calgary, San Jose, and Edmonton? If I'm the player and agent, I feel like I get a better opportunity to prove myself in Calgary (if Ramo walks), San Jose, or Edmonton. With Dubnyk not signed yet, you might be able to add Minnesota to that list as well.
The only real negative at this point is that Kari will scare off many starters or borderline starters from signing in Dallas. Even with a poor season, it's just natural to view his presence as a risk compared to a wide open team like San Jose, Edmonton, or Minnesota, and Hiller doesn't have nearly the firm grip in Calgary that Kari has had in the past. I do believe the team will be less willing to let Lehtonen play out of a slump, but they're going to have to prove that this season for people to take them seriously IMO.
That's why a trade may be the easiest option.