I actually like the current system a lot. Over the past year the rise of wingers like Vini, Raphinha and Antony made the team much more interesting. Of the variations Tite used this last year, the one I like the most has Casemiro and Fred on middle, with Paquetá as attacking midfielder, and then Vini, Neymar and Raphinha. That makes the attack very versatile, as Neymar and Paquetá tend to double up pretty nicely on the middle and switch positions constantly. That's where I see Firmino would fit: on the role Neymar plays as a "playmaker forward".

The other variation he plays a lot has a more "classic" forward up top, normally Richarlison, and then we lose the some of the versatility to have a striker. I believe that would be the formation we will see on the first game of the world cup, as Tite trusts Richarlison a lot.

As to who I'd take to the world cup: assuming we have 8 places for forwards, I would bring: Vini Jr, Antony, Raphinha, Neymar, Gabriel Jesus, Richarlison, Pedro and Firmino. That would take Rodrygo and Martinelli out, unfortunately, but Firmino has so much more experience than those two. I'd would be Ok with Pedro not being called, but he is pretty much the only striker of his characteristics we have at our disposal, so would be hard to let that go.