I've had this thought of how to re-create the 4222 from the end of last season, I think this was our best formation personally. It's probably more likely Pep goes back to a 325 (which he did when Akanji returned), but our attack with the new signings is so potent, I'd not like to abandon the 4222 entirely.
But it relied on 2 high fullbacks, now Ait Nouri is one fix clearly, but perhaps we don't want to rely on Nunes to start (assuming no Livramento), but also want to use our wide wingers (Doku, Savio) more?
This is my potential fix:
In Possession Set Up (4222) Out of Possession Rest Defence (541, could be 532 also)

Other ways to make a 4222 without wide fullbacks is to invert a fullback instead from a 4231 or 4141, but I'm not sure I want to do that either, the best option from that perspective is to play Rico Lewis RB as Pep doens't quite trust Nunes in the middle. I've also had the theory of Khusanov doing this ala Kounde, but obviously that'd be a sort of project development.
This setup borrows a little from the treble system, that started with a back 4 and only pushed up the CB (here Rodri/Stones), tinstead we defend with 5, and push up 3 players, with the CCB easily able to drop to make the 3 on counters.
This perhaps gives more longevity out of Stones and Rodri, as we rotate between them, with Rodri being the clear starter.
Pep usually never uses a back 5 to defend, except... I noticed how often this last season when we lost the ball in our usualy 4231, that a winger dropped to make a back 5 (I've seen Savio, Doku, and Bernardo all do this at various times), so I don't think he is averse to defending with 5, he just hates it for pressing because you have one less.
This is solved by making 4222 the main out of possession shape, as well as the pressing shape (424 he has been using), and only sitting in the back 5 when we defend.