The one advantage the new GM will have coming in is that despite the anchors of the Carter and Granlund contracts, the Pens have a ton of cap space to work with.
According to CapFriendly, the Pens have 15 players already for next team's roster (which includes Nylander, but not any of our RFAs). They need to fill 8 spots, and have ~19M to do it with. So, an average of ~2.4M per roster spot.
Assuming Granlund, Nylander and Carter are all in the bottom six, the 8 spots remaining include:
1 top six winger
1 starting goaltender
3 bottom six forwards
1 bottom pairing defenseman (which I'm assuming will end up being Smith, anyway)
Only the top two of those positions should require more than 2.5M in cap hit, each.
Plus, 3 of those spots are likely filled by DOC, Poehling and Smith, who should all still come in relatively cheap.
So as long as we can avoid signing any fourth line players to any 2.75-3.5M cap hit contracts (*cough*McGinn/Tanev*cough*), they should have plenty of flexibility.
And that's even without trading a single player off the current roster. (I would be astonished if no players were traded off the roster this summer).