I think he could play the anchor role, because I think he's a disciplined and fairly intelligent player.
However, playing Nainggolan that deep would waste his athleticism to some extent and I'll need to see him more to be convinced his passing is good enough to play that role well.
That said, if Juve sign him and Pirlo gets injured, I'd be playing him deep before I'd consider putting Vidal or Marchisio back there.
And I wouldn't really say he's Vidal-esque. He seems a much calmer, more controlled player, but he probably doesn't have quite the same energy Vidal has to get about the pitch for 90 minutes.