pretty sure BUF is content with Lehner as the starter right now so don't know if they'd give up anything more than a 5th or 6th for MAF. Might find a better trade partner elsewhere

Lehner is really good
Buffalo doesn't need Fleury
Maybe with the 2 million retained Carolina or Winnipeg would be interested....
Or even a trade to Vegas post Exp. Draft

BUF is set in goal with Lehner Nilsson Ullmark Petersen and Johansson

I think that trade to Vegas Post Expansion could have to serious interest on both sides. He's not worth the free pick, but a trade afterward might work. Wonder what that would look like? Guess it depends on their overall Cap Hit after the expansion draft is completed.

My understanding (from a friend who follows Buffalo more than I do) is that Lehner has been inconsistent and the Sabres management may not want to commit to a long term contract that he'll probably be seeking. Bringing in a competitor for the starting spot (even if it isn't Fleury) seems like a good move.

Calgary/Winnipeg/LV are all options from a needs/cap space point of view, but no guarantee that Fleury waives his NTC to go west. Carolina probably needs to send a goalie back (AND still needs to have one to expose to the draft) which won't work with the Pen's cap.

Buffalo issue is inconsistent defensive play. They gave up the most shots in the NHL. Their focus is to improve the defense and hopefully that will help out Lehner who actually did not have bad stats considering the barrage of pucks he saw.
There are better trade partners that do not have close to average goaltending aka Winnipeg or Dallas. I don't think he'd waive for Winnipeg just due to location but Dallas is a team that with solid goaltending is easily a playoff contender.