Yes, but this is where the differences between the Kovy and Nash situations come to light. Atlanta had to trade Kovalchuk. They were going to lose him via free agency and they had so much going on internally that they almost had no choice. No one wanted to pay an expensive price for a rental like Kovalchuk. When was the last time a player of that caliber was available as a rental? Mix that in with a GM that doesn't do his research, and you find yourself trading for a defenseman in Oduya that had 1 point in 21 games, Bergfors who couldn't stick in the lineup, Cormier who almost killed someone, and a draft pick. Cormier is turning out to be not much and the ThrasherJets don't even have Bergfors or Oduya anymore.
Howson has the opportunity to keep Nash for as long as he wants. Once Semin signs somewhere he might get a few phone calls with GM's that are a little more desperate having lost out on Parise, Suter, Semin, AND possibly Ryan. I would also think right now that Bobby Ryan is bring in better trade offers given his age and smaller cap hit.
I'd be willing to go up to Greene, Tedenby, Gelinas, and a 1st for Nash OR Bobby Ryan plus a 2nd rounder from that team... Lou has proven he likes to get a draft pick back in a trade where he gives one up. But the fact that they are looking for Couture, Skinner, Kreider/Stepan, and players like that... the Devils might not even get any consideration unless Henrique is included or if the Devils are the only team left with an offer and Semin is signed somewhere and Bobby Ryan was traded.
Like I said, not perfectly analogous to the Kovy trade, but Howson would be hard pressed to keep a disgruntled Nash around, same as Anaheim would with Ryan. It doesn't mean he HAS to, but it certainly lowers the asking price.