A Much Better Alternative - PoT (Proof of Time)

A much better alternative is to institute a artificial time delay of 10 minutes after each added block. Miners are free to hash transactions into blocks (without mining - finding the nonce to solve for a certain level of network difficulty) and broadcast those blocks to the network.  A randomized selector hosted by a super node will select a timestamp. The broadcasted block with timestamp closest to the selected would be the winner. 

This method will achieve the same level of network security and performance without the expensive mining.