As able as he is it could be a big step towards a different style of play if he does move. I think you're always going to be wedded to having two deep central midfielders if you want to play Neves.
You look at Liverpool as an example, Fabinho gets left as the only protection to the two centre halves 90% of the time, I don't think Neves can cover the ground to do that if a team wants him to be the sole defensive presence in that position. Even City had to tweak their setup when Rodri replaced Fernandinho because he wasn't as mobile, they ended up with fullbacks tucked in rather than overlapping so there was extra cover for the centre halves.
You might not get anyone as technically good as Neves to replace him but you might get someone that helps free the team up to do something different. Someone that ends up being a better fit for a potential new style of play. Just depends how that money gets reinvested.