Regardless of what division we are in we will want to keep our best players and add extra quality, there is very little chance Cook and Sharpe (or whoever is chairman) at the time wont do their best to try and strengthen the squad and tie down our key men with a year to go to new deals.
I don't think anyone significant is out of contract except Walton going back to Brighton, who i'm certain we'll try and bring back and Elder who I suspect we wont. So if we do sell it should be on our terms and for a lot of money.
Personally i feel a lot of our players have really developed and improved this season under Cook and if they got another crack at the championship they would fare better. So while it's obvious some players will be more likely to make the step up than others, I wouldn't completely write off the future prospects of anyone just yet. I bet no one at Sheff U thought Leon Clarke would would do anything at Champ level after how he did for us at L1 level yet he's been a huge player for them. Different system, different manager, different team mates, different time can all make a big difference.