Replacing Callejon is complicated for the Partenopei because of his tactical intelligence and attitude.
However, the 33-year-old Spaniard is coming to the end of his stay in Naples and the club are thinking about replacements.
The latest player under consideration is Cengiz Under, the 22-year-old Turkish international who has impressed at Roma.
Napoli owner Aurelio De Laurentiis has inquired about Under and Roma have valued him at €30m.
During discussions about Under, Roma asked about in-demand Napoli striker Arkadiusz Milik.
Roma could only really enter the running if they lose star striker Edin Dzeko, who has been linked with Inter.
Gazzetta dello Sport also mentions Newcastle as possible suitors for Dzeko after their takeover goes through.