Sullivan won't be fired this offseason.
Hextall is more likely, but I've yet to see any indication that FSG is eager to actually put its fingerprints on the Pens instead of just letting the franchise run itself.
If Hextall is fired, FSG will prioritize forward thinkers who will build up a staff that relies on analytics. They did it in Boston and they did it in Liverpool with Jurgen Klopp.
Think Mathieu Darche in Tampa, Eric Tulsky in Carolina, Chris MacFarland in Colorado (likely unavailable now, but they guy they should've hired when they hired Hextall).
I could see them hiring someone like Megan Chayka to a prominent role, maybe a reshaped President of Hockey Ops to design the front office a certain way but with someone like Darche or Tulsky managing the roster.
At this point, if Sullivan's kept on as coach you might as well also let him be GM so he can just acquire the type of players that he will use.
Each department has their own issues, but one of the collective issues with this team seems to be the GM (both Hextall and JR before him) aren't on the same page as the coach with regards to adding to the roster and those additions being used properly.
There are no current coaches who are also the team's GM.
It really hasn't happened in the last decade. The positions are too demanding on their own.