Don’t think you will see this set up on the FL 45S. They have to keep an arm distance from the C63S 4matic EQV+ (What a mouthful) Maybe on the next W179 & by then the C63S will have something new in its sleeve. Batt tech is changing for the better everyday. This is only the beginning. A mild hybrid is a distinct possibility for the FL.
One of my previous comments on the hybrid for the A45s FL was how will they configure it if the hybrid actually uses an additional engine. I am guessing the electric engine would go in the front of the A45s with the battery pack in the back, as a longitudinal set up with the electric engine in the back together with the batteries must require a massive amount of re-engineering. In addition unless MB can use some of the new architecture to substitute for the added bracing the A45s, the weight of the FL version will rocket.