I don't actually want to see either but maybe Cumberbatch could play Q. Somehow the cosmic Q force encounters Khan and merges with his consciousness before his demise.
Whatever the plot I wouldn't mind a Mudd vignette like the Nibiru opening of Into Darkness. Though I think I'll do a spit take if they bring the Genesis device or anything else from Star Trek II/III. I do like some people's mention of the mirror universe because I think that does have a lot of mainstream recognition that it might just work.