Mind EVs & PHEVs are heavily subsidised in many markets around the globe + additional administrative obstacles have arisen for ICEVs, especially diesel cars in many markets (at least locally / regionally).
Not to mention the migration to WLTP standardization in EU market: many carmakers will introduce EU6d by WLTP new / refreshed engines or car models in the Spring 2019 as 2020 MYs.
But yes ... gradual migration from pure ICEVs to PHEVs and pure BEVs is inevitable. But it's market dependant. Somewhere migration will be quicker, somewhere slower. It depends on subsidies, charging instruction, electricity grid readiness, electricity prices, competition pressure.
China ... especially in the biggest cities the air has been so polluted an urgent action is needed. Therefore very aggressive administrative measures to quickly decrease ICEVs sales + increase of BEVs sales have been introduced.