In my opinion:
Anderson, Callaghan and McMillan will leave. McCann will be offered a contract to stay. As for the others it all ifs and buts.
If Kennedy and Wright have good seasons they will be off. Their agents’ actions reflect this. Therefore we need a contingency, is it to keep Swanson or do we pick up someone on a pre-contract in January? The risk there is what if Wright or Kennedy stays. Hence I believe the pre-contract is a non-starter, unless both Kennedy and Wright sign pre-contracts with another team.
Kane and Hendry, I agree they have to prove themselves worthy this year. I believe only one will survive and if possible, we should look for a striker on a pre-contract.
Craig needs a good season to get a contract.
Swanson as stated above depends on his performance and what happens with Kennedy and Wright.
Max Johnstone, I too have idea but I do not think it is significant in the big picture.
Holt and Ralston will return to their parent clubs
Therefore next season, we could be looking to replace 7 players
In defence Ralston.
In Midfield, Kennedy, Wright, Craig and Holt (arguably could be one of our starting midfield selections)
Forwards McMilland and 1 form Kane and Hendry.
But as you said for the sake of conversation, because if worst scenario happens and we get relegated all those that have a relegation release clause; Clark, Kerr and O’Halloran will also have to replaced.