Postpone De Ligt to 2020. I'm sure he doesn't mind growing and developing @ Ajax for another season. If that's not possible, go the PSG way. Loan for 20 million + obligation for another 50 or something. Defer payment to a later date, and we don't get fucked by FFP.
Go all in for midfield. Ndombele and Ramsey is good. Sell The Tajine Twins (I'm not sure anyone will pay more than 30 for Can, and we'd be lucky to get 10 for Khedira). Tonali, if we have enough money, for depth and Italian talent.
Defense isn't getting any younger, and we're always one Chiellini injury from a disaster. Rugani, Romero, Chiellini, Skinny Legs, and some scrub. Barza retires. De Ligt can come in January or summer of 2020. Rugani, De Ligt, Chiellini, Bonucci, and Romero. We'd have 3 very talented and young CBs. Defense set for the next 10 years.
In attack, keep everyone except Costa, and possibly Cuads. Chiesa could come in, but he's not a necessity. If he costs anything more than 50, street.