According to WCF the current M5/6 will be the last to be offered in manual form, BMW say that uptake is only 15% and it's not cost effective to offer this option in future though the M3 will continue with this option.
http://www.worldcarfans.com/112062145621/bmw-m5-and-m6-manual-transmission-axed-on-next-gen
http://www.worldcarfans.com/112062145621/bmw-m5-and-m6-manual-transmission-axed-on-next-gen