Reports say Cavani has already agreed with Atlético for a 3-year contract. Apparently Cerezo is trying to convince PSG to let him go in January on the cheap (€5M), because his contract expires in July 2020. Not sure how are Morata, Félix, Costa, Correa and now Cavani going to play together.
I think Morata produced this half season what he did the second half of the previous season, the problem is that what they get from Félix in goals is nowhere near what Griezmann could do (around 1 goal every 2 games) in the defense focused 4:4:1:1 Cholo plays. Maybe they will have Morata at CF, Cavani as second striker and Felix alternating as attacking mid-fielder or as reserve second striker.
Matic is in the same situation as Cavani with United, but I guess Atlético will wait till July.
They get experienced quality players, for the cheap, while also buying young players.