Do you think we'll see Pep try that very often though as we can only really push both fullbacks inside when Walker isn't in the team which isn't very often these days.
I agree though, I'm liking the idea of us using such a brave strategy when we know the opposition are just going to sit really deep. And like you mentioned, we can always switch back to the 3-2 formation if they start to commit more men forward after we score for example.
Maybe it's asking too much in his first season but I wonder if Gvardiol is capable of playing inside to a similar standard as Stones and Akanji. It's a demanding role but he's certainly got the technical ability to do it.