It's a blow to the Penguins, but not the end of the world in losing out on the two.
So, this off-season the Pens have lost the 50 points Jordan Staal scored, the 48 that Sullivan contributed, as well as a top 4 defenseman in Zbynek Michalek. In return, they've only replaced it with Brandon Sutter.
General Manager Ray Shero will move on to Plan B. A lot of fans have wondered about Shane Doan, but it seems his heart is still in Phoenix. On top of that, he's an aging player with declining stats, possibly questionable skating for the Pens system and he would be seeking a 2-3 year deal and a lot of money. Alex Semin isn't a Dan Bylsma type player, to put it mildly.
The Pens may have to look to the trade market. Bobby Ryan from Anaheim could be on the block, but the Ducks probably want an NHL ready offensive player as the center-piece of the deal and the Pens don't have that to offer. Rick Nash might be floating around too, but given what Columbus might be seeking (plus Nash's age and bloated contract) he's not an ideal fit either.
Mike Colligan suggested seeking out Chris Stewart from St. Louis, and that could be a possibility.
No matter who the targets are, it seems the trade market could be more appealing than the free agency. With Parise and Suter off the market, not many options make sense for Pittsburgh $$ wise and ability wise.