I could see him being available if NSH remains out of the playoffs, but this does not get it done.

If Predators remain out of playoffs, what would they want from Capitals for Jarnkrok?

If NSH is willing to retain 50% of Jarnkrok's cap hit, then I could potentially see NSH getting a similar deal to Goodrow/Coleman/etc. Maybe a 1st from a contending team? Maybe a pick and a good prospect? Not really sure what WSH is willing to give up. Laviolette really liked Jarnkrok when he was in NSH, so maybe WSH would be willing to give up more than other teams considering their familiarity.

And what about trade: Haula for Siegenthaler + Panik (XY% retained)
Is it possible for Predators?

I think you'd have to take the retention off of any Caps deals and give up maybe our 2nd round pick instead. Two things I've noticed about the Caps org is that they don't buyout anyone and they don't retain salary either. I can't remember the last time they did that. It must be the policy of the owner I would guess.

I don't know if there is a place for Siegenthaler on NSH anymore -- I would've liked him to start the season, but as it stands NSH has Josi -- Ekholm -- Borowiecki -- Davies -- Farrance (hopefully soon) on the left side. I don't really know if Siegenthaler is going to supplant any of them (for better or worse). So I don't know if he would be a target for NSH. I'd rather probably just have a 3rd rounder for Haula, or a 2nd if there is enough interest around the league. I don't really see why NSH would be willing to take on Panik and his contract without any compensation.