Getting him now when he is going to fall off due to his age would be self-destructive, he would still prefer to play 90 min every game and to have a huge wage like in Bayern but if Bayern are ready to get rid of him we shouldn't fall for that signing.
If we are to sell Morata thinking that to invest in a young talent was a total failure and to change the strategy into signing an old player instead, that's just going from one extreme to the other.
IMO, if we get Sarri, he could maybe influence our transfer targets and help to get Icardi instead that saw how Sarri likes to play. He is 25 years old, entering his best years and there is basically no way that he would flop like Morata since he has been a standard striker and the captain of Inter, he's not just a top striker with 29 goals this season in the league but he was also a leader-type player that Chelsea needs really much ever since Drogba left.
https://www.football-italia.net/121726/inter-prepare-icardi-renewal