The huge loss for them is Salah upfront. I don't think they'll miss Manolas that much. Both Fazio and Rudiger outperformed him last season. Whilst Paredes although talented was still behind the pecking order.
Honestly , if they retain their midfield core-Nainggolan,Strootman, De Rossi, add Gonalons on top off it, and add a quality forward upfront, they definitely have the squad to atleast make top 4.