Guess that depends how highly you rate Letang. Imo, next season he's probably going to be the guy who played the 2018 part of the RS at worst and at best, he rebounds to being the guy who a point per game through the first season and a half he played for Sully. That, to me, is worth a hell of a lot. Less than if he was deffo the best case guy, but I think the Pens are better off taking that gamble than selling to another team relatively cheap so they can. Worse case scenario - he's about the same as this year, we trade him then and I'm not sure how much the value drops. Best case scenario - Awesome dman. Probably somewhere in the middle, but that's worth having, and having the better player is more important for a win now team.
Most Letang scenario is he has a Norris worth system than breaks his neck with a sliding block on a Weber shot in the 81st game of the season, but I digress.
Anyhoo - there's plenty of Pens fans who I think wouldn't demand that much extra on top of Gardiner, but I would. I shan't claim I'm an expert and it should be the way I say so - but I do get a feeling the Pens org are so minded.