If De Bruyne avoids injuries, which is a big if, for sure he would be one of the best Serie A players despite the age. I'm not a Napoli supporter but I have to admit that it is a great move, he can really make a difference, especially in the big matches.
I’m a Napoli supporter, and i think Napoli hasn’t had such a good signing in a long time. Of course, Kvara and Osimhen are very good signings, but a class player like KDB is truly a great addition. As you say, if he avoids injuries, he could become the new MVP of the league.