I've read that this switch to PoS is not a full transition. Etherium will still be largely operate under Proof of Work, allowing the first ever cryptocurrency to run both on PoW and PoS simultaneously. I think the numer i've seen is for every 100 blocks written to the chain through PoW, 1 will go through under PoS protocols. This hardfork is necessary to move the platform away from PoW, which I think everyone is excited about, rightfully so!