Agreed, they even did it in the W203, extending the front end to accommodate the M113 V8 for the C 55 AMG, using the nose from the CLK.
If Mercedes want the W206 to accommodate a V8 then it would not be a problem when designing the W206, nor in the future should demand dictate.
It’a a very conscious decision to switch to a 4 cylinder hybrid. Why wouldn’t they exploit the potential for marketing using references to hybrid technology from their F1 team.
Now is a perfect time to do that, incredible F1 success and upcoming Project One, greater interest in hybrid tech to boost performance rather than maximise economy.