The C-Class had been facelifted for 2019 and there are typically at least 3 more model years before an all-new redesign goes on the market, so based on that the new C-Class would be expected sometime in 2021 as a 2022 model. Whether it will be a C53 or a C43 has to be seen and also what powertrain it will get. A fairly substantiated rumor is that the next C63 will get a 4-cylinder hybrid powertrain, and the C43/53 will get a detuned version of that. The C43/53 will definitely not get a 6-cylinder if the C63 gets a 4-cylinder. Unfortunately, the emissions regulations in Europe are becoming extremely tight. Starting in 2021 the fleet average CO2 emission limits are 100 g/km. Mercedes-Benz as a whole, which includes AMG is currently at 138 g/km, so they have to significantly reduce that or start paying steep fines. It's already being discussed that the AMG lineup may get severely gutted in order to meet those targets. Here's one article discussing it. I would be very careful with expectations for the next generation of these cars. The car manufactures have had several years to prepare for this, but they have gone with customer demands instead and built powerful high emission performance SUVs/Crossovers and other cars that didn't help bring the average down and now the guillotine is about to drop.
https://drivetribe.com/p/mercedes-to...QdqyG7X_fRJLAQ