The problem with a series set at Starfleet Academy is that you will have to do completely different types of stores than Trek fans are used to seeing in a weekly Trek series.
You can't have cadets out saving the universe every week without jumping thorugh some pretty big logic hoops and/or straining credibility. I mean how often do we see cadets/midshipmen at West Point or Annapolis out solving problems of national significance or saving the world in a heated battle? You don't. they're in classes studying, and don't even have time for much of an interesting personal life for most of their time in the academy.
Nope. Might work as a one-off movie, but for weekly Trek stick to active crews out in the Fleet.