Rangers absolutely have to lock Yandle up long term or move him at the deadline...cant have a #1 defenseman walk for nothing in the offseason...horrendous asset management if they do.
If they're in a position to contend they're not going to move him even if they know he's not going to re-sign. the only way that happens is if for some reason another team wants to move an equal player in exchange.
I'm not sure why people don't generally understand this...contending teams don't move top players at the trade deadline because they might lose them later solely for the purpose of "asset management". It's dumb to do so. The goal is to win the cup, and Yandle on the team gives them a better change than Yandle not on the team.
The Rangers moved Callahan not just because of his expiring contract but because they saw they could use him as part of a trade to acquire a better player for their cup run. If there's even a vague chance that Yandle is traded it will be a similar situation...the Rangers moving him for a comparable or better player, but also realize that would mean picks or prospects going the other way as well.
They're not going to move him for depth players or picks/prospects. And it's not horrible asset management to play it like that. Horrible asset management is making your team worse right before the playoffs when you have a legit chance to win the cup.