I´m aware of that, which is why I´m saying: we need two new CB´s, but it would be unrealistic to expect two signings like Milenkovic. Therefore, I wouldn´t mind signing Vestergaard as one of the new CB´s.
Now, I´ve been doing a small research in some Fiorentina sites. The club is a complete mess right now. Prandelli just resigned as manager for health reasons (after a defeat against AC Milan on Sunday, and a panic attack). The Viola are in 14th place and will fight against relegation from now on (even though they have more than enough quality to stay in Serie A).
About Milenkovic, their fans are sad, but they already consider the CB will be gone in the summer. He´s not been playing well, which is expected, really - considering that the whole team is also playing bad, and the contract situation usually change players approach to things one way or another (just see Eriksen). He also plays on the right of a back 3, which is not ideal.
That said, every single one of their fans would keep Milenkovic if they could.