Ziyech isn't a problem for Chelsea they have loads of players in forward positions. City the same with Mahrez. Liverpool may suffer but I reckon one of Salah or Mane will be sold and will be replaced.It’s going to be a problem for most PL teams though tbf.
Chelsea losing Mendy and Ziyech, Liverpool losing Mane, Salah, Kabak and Keita, City will lose Mahrez, Leicester will lose Iheanacho, Amartey, Mendy and Ndidi, Utd will lose Diallo, AWB and Bailly off the top of my head.
Obviously we’re losing four but most of our rivals for top four will be hit hard as well.
AWB is plays for England so unless England are competing in the compeition he won't be missing. Bailly is rubbish and will be replaced this season.