The 25-year-old Frenchman was linked with a move to Stamford Bridge throughout the most recent transfer window but ended up staying put.
Napoli president Aurelio De Laurentiis recently revealed that Chelsea even offered £51million for the centre-back, but still he refused to sell.
And now, after a summer of speculation, Koulibaly’s agent – Bruno Satin – believes his client may commit his long-term future to the Italian club.
“Is there a release clause in his new contract? I won’t go into that, it’s confidential. Koulibaly could stay for life, you never know in football,” Satin told Radio Crc.
“He’s always been at ease in this city, the people love him and he has a great relationship with his teammates. There are no problems, he has this season to play.
“Don’t forget there’s the Champions League, so he’s looking forward. He has some very important motivations. He knows he has the confidence of the coach, that’s super-clear.”