Per latest the special edition X6M will have the M3 CRT like confiig. KERS, optional carbon brakes, carbon roof, more HP, and the list goes on.

There is not even a rumor at this time that there will be X6M like special edition for X5M as well but I have a feeling BMW will probably have one before the production of X5M ends.

M3 sedan production ends in October, and we have seen few special edition M3 sedans in last 6 months, introduced in limited editions in different markets.
Whether X5M and X6M get similar treatment before they disappear remains to be seen.