As little as my regard is usually for RGs skills in negotiations, I think Kurt and his agent are to blame here. Unless the numbers being bandied about in the media are grossly inflated, his demands are completely unfair and should not be met.
Were I in charge of the Cards FO, this is what I would do: Get together the best possible offer we would ever offer Kurt. Make sure that offer is not ridiculously high because, believe it or not, we don't have to re-sign him to be successful. Tell Kurt and his agent that this is the offer on the table. If he wishes to accept the offer at any point he will be welcomed back with open arms. Also let them know that if, at some point in FA we find a couple of really good players that we want to bring in, or if we get an extension figured out for one of our guys, and if that money would proclude Warner's contract, that we're ready to move on. Let them know we won't wait around for him to sign before we conduct business. Unfortunately I don't think we'll do that, but I hope that's how our FO approaches the situation.