I'd say either Zaza or Mandzu leaves. Definitely not both. Neither will be starters now, so that doesn't really matter.
We had continuity for 4 years, up to that CL final, and then Tevez and Pirlo basically retired, and we've been reshaping the team ever since, to set up for the push of Buffon and Barza's last couple years. We have a perfect mix of experience, prime years, and youth right now, imo.
The only mistake was selling Vidal if we didn't have guarantees that Pogba would stay at least until 2017, if not 2018 and the end of Buffon's era. Selling Pogba is just fine and dandy... only we should have kept Vidal if we were planning on selling Pogs.