In one of the pinned blizzard posts Kaivax has already stated that:
So just opening more servers at current phase is what they are doing already… and it’s screwing things up for those servers who had a ‘balanced’ PvP experience.
The reason that existing servers would not die is because they have LOADS of players who just got rank 14 and have invested over 120 days /played. they are too invested in their current trek to AQ and beyond. Fresh would only leach away disgruntled or behind the curve players FROM ALL OVER to have a second go at Classic.