Next generation all-wheel-drive M5 is not out yet, but it already looks it will fail to regain performance sedan leadership for BMW.
Regular G30 is enjoying favorable reviews which may help G30 M5 win in sales - something BMW would, certainly, appreciate after losing its status of largest luxury car manufacturer to Mercedes-Benz.
Performance leadership is where G30 M5 will face tough competition from Porsche and Audi, particularly from the Panamera Turbo S.
I doubt that BMW will match 680 - 700 horsepower output (allegedly the new M5 will have 600 PS), and BMW will certainly not match Porsche in perceived technological advancement. Fully-electric is where industry is going and high performance hybrid is a stepping-stone towards that.
Porsche don't have Tesla Model S rival yet, but they are developing one (Porsche "Mission E" project) and it should arrive circa 2020. BMW don't have anything to counter Tesla Model S either and it looks like in 2017 they won't even have the intermediary performance hybrid.
M division are still a step behind competition and, if it wasn't for the xDrive, it would be 2 steps. And 2 steps is a lot of steps in market segment where it often comes down to photo-finish to determine who beats what and which sports sedan really deserves to be called "world's fastest".