I'm very sorry for Lukaku, he's a player I really like and appreciate for his mentality and his physicality, he's great and I think that without him Napoli could suffer and not a little, I also believe that they won't find a replacement easily, now they have to adapt more than ever
Lukaku's injury doesn't seem a serious injury. Yeah he got injured due to the bad landing, but he can still walk after he did it. I guess it's only a minor injury, and his knee is fine. He will be playing in Napoli's first game. Don't worry!
He has been Napoli's key to win last season. If he injuries, many doubting Conte's chance back to back scudetto. We will see him soon.