His contract expires on June 30 2027, that's still long enough for Napoli not to worry about losing him. On the other hand, Khvicha Kvaratskhelia still intends to play for Napoli next season, so even if Real Madrid or some other European team wants him then of course he will try to refuse. But Napoli might sell him when they get a lucrative offer in the next few seasons.
With the remaining contract duration three years later, I don't think Napoli need to worry about the future of their favorite winger Khvicha Kvaratskhelia. However, with quite impressive performance this season with contribution of 14 goals and 10 assists from 33 matches. I think Kvaratskhelia's transfer fee is very expensive and there is no guarantee that next season the transfer fee will still be the same because it depends on his performance with Napoli.
Its more profitable for Napoli sell him above 60 to 100 million euro due impressive performance from Khvicha Kvaratskhelia last season, but has chance if next season his performance drop, Napoli has potential loss transfer market values from Khvicha Kvaratskhelia more than 2o million euro.