This is where we really need the Head of recruitment in place - NOT because he would be making the calls on retention of players, that will be Cooper and Birch. However, knowing the individual players and potential costs of replacement really influence the value of the contract you offer.
For example Mulder and Nordfeldt could be dealt or allowed to walk if there was a low cost replacement keeper on the horizon - if the market for keepers is high then we would potentially take a very different approach to contract extensions with the pair.
For a lot of the others Cooper and Marsh is getting to know them right now and I expect his opinions will give Birch his "marching orders" with the priorities for extending contracts.
I agree with @SpringheeledJack that (projecting forward a year) the really important single player to retain or replace is VdH as his influence extends way beyond his ability on the pitch. The three mentioned whose salary we need to offload NOW is urgent work and you can add Carroll to that list.
For the others they either sign or they walk in 12 months. I don't see any likelihood of a fee being received for any of them in summer 2020.