I honestly wouldn't be surprised to see Nunes in a midfield 2 as well, physically he has always been suited to it.Pep talked about Matheus being used as holding midfielder more in future recently.
I think after he resurrected his career at City and delivered stable results as a RB, now he is ready to return in midfield and become one of the best midfielders in football..
During his first season he was always loosing physical duels, slipping a lot, didn't know system and teammates that much and etc. But now he is one of the senior members of the squad, has experience, has regained confidence, knows system well, so why not ?
Especially when futures of Rodri and Kovacic aren't certain and Bernardo has already left.
And mentally I think he matured his game as well.
I have this theory in a back 4 that Maresca will prefer Guehi there anyways to tuck into a back 3, leaving Nunes as a rotation option at RB and midfield.