I think pretty much any club could struggle to hold their best players these days. Man City, maybe Liverpool an exception. Chelsea could easily lose Hazard to Real Madrid, for example. So if an offer is large enough and the player hints they would be interested, not much we could do really.
I'd like to think Brooks is a grounded lad though, he knows this is a good place for him to improve and that he has years ahead of him. So would hope we can keep him for another couple of seasons. And I hope when he goes, its to someone like Madrid, Barcelona etc, as I think he can be that good.