The Mercedes-Benz Vision EQS concept is a sneak peak at a future EQS luxury sedan that is completely electric and sits at the top of the Benz lineup before hitting Maybach. The EQS however won't be replacing the S-Class, but instead sharing the pedestal with it.
The production version of the EQS likely won't arrive till 2021 as a 2022 model year. In the meantime, a new S-Class is expected possibly at next year's Geneva Auto Show with sales beginning for the 2021 model year. While the next generation S-Class will be available with some sort of hybrid power, a fully electric version of the car is off the table for now, diverting all of the EV attention to the EQS. Further differentiation will happen with the EQS taking a more futuristic look while the S-Class retains its more stately gravitas.
This two model strategy will continue for the main meat of the Mercedes-Benz lineup with an EQ model equivalent being available next to its conventionally powered counterpart with the EQC being the first to enter the fray.