Jan should be careful. He might have been our best defender for a while, but now I think there's an argument that he's the least talented in our starting back line (depending on your view of Walker).
We've got the best (in terms of overall talent and chemistry) centre-back pairing in the league; surely he'd want to keep that going.
At 29 though you'd expect this would be the money deal. He could command a big salary at our competitors or a major European club.