Mercedes is said to be dropping the Bosch-developed Sensotronic Brake Control (SBC) by the middle of next year, with a conventional hydraulic braking system to appear on the CLS and facelifted E-class.
The brake-by-wire system is probably best known for causing two of the largest recalls in Mercedes history, with software to blame in the first and ominous "unspecified problems" triggering the second campaign. SBC was thought to be a significant competitive advantage when introduced four years ago, but quickly fell behind relative to technology advances in conventional brakes. Customers were said to be wary of the by-wire system's reliability, and I don't recall ever reading a review where the system received praise.
Will this mean that the future of brake-by-wire in general is in doubt? Certainly, this doesn't bode well for any other manufacturer that's looking to put the technology into production. In the auto industry, there's typically little tolerance for failed attempts at early adoption.