I would only add that my desire to trade Hanifin stems from wanting to rebuild the blueline. I agree that in a vacuum, trading Hanifin is a mistake. You are not going to get replacement value, and you are not going to be able to fill that hole via FA. I'm skeptical you can fill it with Kylington.
For me Hanifin should be traded as part of a plan to rebuild the d core. Use either other assets, or assets you get in the trade, to go target a younger dmen who you can give that opportunity to. Between Rasmus and Weegar, the Flames have their puck moving, push the puck but play well at both ends dman and they don't need a 3rd in Hanifin IMO.
That and I just don't see Hanifin signing a good deal, but trading him absolutely needs to be part of a bigger plan.