Someone under a fixed term contract can't simply "quit" the contract. Both parties can agree that the contract finishes early, but if Carlton decided to play hardball with Yarran they can enforce the contract onto 2016 & their ain't much Yaz can do about it.
That's not to say a deal won't get done - think a deal will get done whatever that deal is, it may be with Richmond or it may be with one of the Adelaide clubs who are also interested, but Yaz doesn't have the same leverage as a player out of contract.
The problem for Carlton is that he doesn't want to play for Carlton, the problem for Yaz is that he's under contract, the problem for Richmond (if they really want Yaz) is there has to be a mutually agreeable trade.
I do find it strange that the Tiges are declaring it will get done without a first rounder likes it's a "done deal," even though Carlton have declared they want a first rounder. Which means, at this stage, it's a matter of who blinks first, which will get murky if other clubs get involved - let's not forget trade week hasn't actually started yet.