According to a report on motortrend.com, it seems that the next BMW M5 is set to have an automatic transmission, rather than a re-worked version of the double-clutch transmission (M-DCT) found in the M3.
The explanation behind this being that the M-DCT unit can't handle the amount of torque being produced from the M5's twin-turbo V8 engine. A major revision to the gearbox would have been required, bigger actuators would have been needed to beef it up, but at the expense of shifting times (and BMW's budget).
In a perfect world BMW would use a proper manual gearbox instead, putting driver involvement first - like they used to. But if BMW end up using an automatic gearbox, it will no doubt irk the M enthusiasts. Let's hope it is nothing but a cruel rumour.