Suspect we'll have a decent chunk of wages to play with:
Contracted to 2018 - Johnny Russell, Darren Bent, Chris Baird, Jason Shackell, Jamie Hanson, Kelle Roos, Joe Ledley
I recall hearing that Hanson had been offered a new contract, so we'll see a pittance in for him if he doesn't sign up - don't see any of the others renewing, save for maybe another year for Baird and/or Ledley. I can imagine the bolded three are on a fair amount each.
Contracted to 2019 - Craig Bryson, Andreas Weimann, Jacob Butterfield, Bradley Johnson, Nick Blackman, Marcus Olsson, David Nugent, Curtis Davies*, Tom Huddlestone*
I don't see Butterfield, Blackman or Bryson staying on beyond the end of the season. Would be nice if we could get something for this pair, but doubt we'll breach £1.5-2m for all three.
The rest will probably depend on what league we finish in this season. But I'd daresay Johnson and Weimann will see an extension, with the *optional year taken with those two.