And regarding Lookman, I think if he leaves Atalanta, it will indeed weaken Atalanta. And in my personal opinion, Atalanta will even struggle to secure a Europa League spot if they sell a key player like Lookman.
Atlanta after many successful seasons will face with a first challenging season by losing the head coach and many star players. Atalanta need to work hard in order to repeat success like Sevilla did in many years. Detecting young and unknown players then selling them for money and replacing them with new players while still maintaining very good quality in many years.
Atlanta have no other choices than relying on their scout team in order to bring good new players who potentially can grow up and become new Lookman, Rettegui and more. Losing Gasperini is very challenging for Atalanta and it is like they will have to replace many important people in the club within a short summer season.