We sign Sancho now, then we have an attack that's 18/20/22/24
We would have 4 players that can play in each others positions at a good level and interchange at will. You have 4 players that score goals and would assist each other, our bench would have 1 of them on it at all times when everyone is fit, what a position we would be in if we had that standard of option sitting on the bench.
Also realistically all our most expensive positions in the team will be filled with quality, with 4 players for 3 positions in the attacking 3 & 3 top players to fill 2 spots in the attacking end of our midfield.
Realistically after this, we could make our summer transfer budget a lot less going forward, with refinements rather than massively expensive signings needed each year.
after this all we would need is another DM (or CDM to some, personally I've never heard of a DM playing RDM or LDM, it's always been centre, so in fact putting the 'c' in front of 'dm' is pointless, but anyway I digress) as matic can't go on forever, a CB to partner maguire & left back to provide competition/cover for shaw.
It wont happen all this window, but if we can get these positions filled in january/next summer with possibly another signing that's a promising young man who wont cost much, this time next season we could be in very good shape. But it's a lot easier said than done & a lot can happen between now and then.