Even if Stones and Ake remain, their minutes will be phased out. They simply cannot sustain the intensity of competing for trophies on all fronts, week in and week out.
I hope that we enter the season with Dias, Gvardiol, Akanji, Khusanov, and Reis as the 'main' group. Reis is really the one I am looking forward to seeing more of. He strikes me as a player capable of bringing the ball into midfield and being able to deliver the kind of passes that will split the opponent's press. Khusanov, I see much more in the Walker role as the last man - the defender that you use to shore up shop against the counter as the ultimate in physicality.
At full-back, Lewis, Nunes, O'Reilly is a group that needs adding to. I would personally like to see the promotion of Mfuni, but an experienced player would help.