It sounds like the Kalidou Koulibaly saga is about to come to a very productive end. The Genk central defender has been linked to an €8 million move to Naples from Belgium for weeks now, and if today's news is any indication, the links will become reality shortly.
Napoli's official website has indicated that not only has Koulibaly visited the club's training facilities at Castel Volturno today, he has been given and passed a medical examination in advance of finalizing a move. That would indicate that a deal has been agreed between Napoli and Genk, as well as personal terms with Koulibaly.
For those just catching up with the rumors, Koulibaly is a 22-year old French central defender who has starred for Genk the last two years, though his form has been somehwat up and down this past season. He's tall (6'5") and strong, and screams of a projectable talent. He's still fairly raw (the Belgian Pro League is arguably somewhat below him in quality) and needs developing, so likely wouldn't be a regular starter next season. Down the line, though, he could be a very good talent indeed, as he's one of the best French defense prospects this side of Kurt Zouma.
This is a nice little way to kick off the post-season. The deal of course cannot be finalized until the transfer window opens on July 1st, but everything can be agreed and set up before then. Given today's news, you should expect to hear of that agreement before too much longer.