My gut feel is that this won't happen but, putting our 'emotional attachment' to Fonte to one side for a moment, it could well be a shrewd move by the club if they were to let him go as his monetary value is probably at a peak right now and if we get VvD we'd still have a decent clutch of CBs on our books. In other words, from a pure business point of view it could be argued that now is the right time to sell him.
That said, and as I say, I can't see it happening as Fonte is much more important to the club than his monetary value IMO, but there again, similar sentiments applied before we let Rickie go...