The fact Trouba is captain is going to make anything and everything harder with him. It is beyond savage to buyout the team captain. It is a weird look to trade the team captain, let alone trade him and retain money. I know that people will scoff those things off but they are real. It doesn't mean that it can't happen, but it is a VERY complicating factor.
Regarding lindgren, I think the comparisons to staal and girardi are unfair. Lindgren does not have offense in his game but he provides more than either of those two guys did, and for a team of vanilla players he stands out as someone with some actual bite and pushback. There is also a consideration to who he plays with. Most say that because he plays with fox it makes him look better, I would also suggest that people consider if how he plays helps make fox better/more comfortable to play the way he wants to. He trusts Lindgren and whenever he has been paired with others he has been noticeably worse. If someone can name a legit upgrade to lindgren that is obtainable I will hear it, but that player was hanafin and he is gone. You don't dump lindgren bc you want to upgrade him without actually having an upgrade. There is room to sign him and less than max term and get good years out of him.