Don't think we'll be looking to sell any of them in the summer. Think we'll try to extend Salah, Mane, and Firmino, but could be tricky as we can't give them all big mutil year contracts. Firmino is probably the easiest as his stock has dropped so a shorter contract on a wage that reflects he no longer makes the first 11 is probably doable. With Salah we'll have to make him one of the highest paid players in the world and give him a long contract. Mane could be tricky unless he's willing to accept a 2/3 year contract without a huge pay rise. We'll have to reward Jota with a pay rise as well.
I have a feeling that the arrival of Diaz will help Mane find another gear. Nothing like a bit of competition and people suggesting you're going to be benched to help a champion like Mane find another level.