No, there will be only one coin.
It will be a transition from POW consensus to POS. They are planning to make it completely miners free. They plan to do it in 2020. I do no think it will be possible in 2020.
Only reason to price dump is mining and I think they will do it in 2020. This update isn't only improve proof of stake, transaction speed per second and more privacy will add in Ethereum blockchain 2.0. Besides Ethereum 2.0 next year has plan of Vitalik Buterin is two another hard fork. All are coming in next year.