Spalletti will not play a 433. Extremely unlikely. He has explained in depth many times why his whole career he has developed a 4231 as his main tactic, and won't easily start over at this point. Why would he, after all?
That is why Brozovic and Mario struggle to find space, while he would have very much liked to keep Kondogbia (who plays best in a 4231.
The player Spalletti needs is an energetic midfielder with good shooting skills and big lungs to play in his atypical trequartista role, where he always adapted player who previously had been defensive midfielders or central midfielders. That's the player we lack at the moment, and why we might try to loan Ramires from China.
I don't want to get into technical nitpicking over 4-3-3 and 4-2-3-1 because the reality is, it's about player characteristics in the roles. At Roma last 1.5 years he had them, and for all the seasons in Zenit and for the seasons before with Roma, his system works really well when he has 3 in the middle with 1 DM-like player, 1 box-to-box CM player who can be a little defensive, and 1 box-to-box CM who can be a little more attacking.
If you want to go into semantics and call his last Roma 4-2-3-1, go ahead. Reality is, it played more like 4-3-3 because De Rossi took DM, Strootman played CM-DM, and nainggolan played CM-AM. Go back to Zenit and he had Witsel as pure DM player. Before Witsel, it was Denisov as pure DM and back then they were calling it 4-1-4-1 formation (again, semantics). So really, he always had a pure DM player, and a really good one at that.
The reality at this Inter is, we don't have a DM like player. This is causing all the unbalancing and before getting someone attacking, we really need to lock down the defensive side of the midfield. I think people maybe surprised if we do get a quality pure DM, how much that will unleash Vecino, Gags, Brozo, Valero etc... offensively.
Speaking of tottenham players, I really want wanyama. Ideal pure DM for us. I like william carvalho too, but he is overpriced.