If it comes to needing a replacement, Xabi Alonso would make a fine job of it.
I dont know, bear with me for a moment
So currently we got a goddamn strong 3man midfield right ?
But as we noticed, without pirlo, we kinda struggle to build up the play, even with bonbon long balls.
SO in short, we could say we need pirlo as a regista/deeplying playmaker, cause vidal and marchisio arent that good at making the play.
Now, thing is, we got pogba. He kinda replaces marchisio in the future, hopefully beeing defensively and tactically around as good, with added aireal strenght.
BUT most importantly, we have seen Pogba's cool on the ball. He can collect it and play it on, and he will do that much better then the other two did.
He's not a playmaker, but without pirlo, the build up will be better.
SO why am i saying this ? We'll because currently we need a deep playmaker, but with vidal-pogba, when pogs has matured and developped more, we dont neccecarely need the playmaker to be that deep on the field.
We could very well have a playmaker who playes a much more advanced role then pirlo.
A trequartista, or a regular CAM, it can all work.
Pogba has shown he has that long ball skill, and shows alot of talent in distributing it. So we wont have that many trouble finding our CAM/treq or SS(tevez) in order to build up the play.
Furthermore, a CAM/treq has the distinguished advantage, that we have more finishing skill up front.
So yeah, xabi alonso could be nice, especially on a low price, BUT, if we want to keep vidal-pogba and build an empire around it (we should) we dont need to replace pirlo with a regista as long term solution.
No, we could replace him with a short term regista solution, to ease the transition, and a long term CAM/treq solution.