this is a myth on hf boards where people believe that picks and prospects are better assets for playoff contenders to collect than players that actually have immediate impact.
this whole "not getting anything for him" is not how NHL teams think. Besides what you get for him is an impact player to help the team's playoff chances now.
Notice how playoff bound teams give up picks and prospects for rental players? they acquire said players at the deadline, and often times they leave without "getting anything for them" ... that is anything besides their impact for a playoff run!
Cammy is a very valuable player in Calgary right now... he's got chemistry and fit in that system and has been a very productive part of a playoff team that has Cup aspirations. If he was on a non-playoff team, even if he said he's going to test the UFA market, he'd still be valuable to a team like Calgary - especially if they knew how good a fit he is on the team.
Teams like Calgary acquire "rentals" like Cammy whether they can re-sign him or not. Teams like Calgary don't trade impact players like him just so they get something for him because their value in a playoff run outweighs the market value you get for rental players at the deadline.
That's the big myth that this whole boards seems to overlook. For team like the Canucks with Ohlund, or Calgary with Cammalleri, keeping these guys is like making a big deadline deal for free. The subtraction of both of those guys from their respective teams is significant, and even if you're using them in a trade to upgrade, you're only hoping that the player you bring back can equal the void left by the player you've traded to get them.
Right now, the Canucks and Flames are buyers, and that means guys like Cammalleri and Ohlund won't be dealt unless it's a hockey deal.
As much as I'd like to see us not lose Ohlund to free agency, it's much wiser to keep him here, hope for a strong playoff run, and resume contract talks after this season.