I may be getting pulled in the wrong direction by the marketing but I am starting to suspect he's neither Khan nor Mitchell at all and that they've been using the fire of fan speculation as a deflection.
Either that or they've been massively reconcieved.
'If the Apocalypse starts, beep me!' - Buffy Summers
'The sky's the limit.....' Jean-Luc Picard, 'All Good Things'
courtesy of Saquist