Theoretically the nanotech does not have to create matter at an elemental level (like a Star Trek replicator does) for the dead Cybermen creation - all the material that made up the corpse would have decomposed into the surrounding area. It's just a matter of putting it back together again and recombining organic molecules - based on whatever scanning technology Missy was using to capture a mind of a human (or mostly human in the case of the robot in Deep Breath) at the moment of death.
We saw that only a percentage of graves resulted in the Cybermen, so I don't think the technology was advanced enough to do that - only those corpses that were still relatively new* could be converted.
* Not sure of the precise timescales, but probably only a few years, a decade or two at most.
I think all of the above contributions make excellent points. I think my other problem with nanotechnology is the difficulty with putting boundaries on it. Yes, if it was that good you can just chuck a mini handful into someone's face and they would instantly turn into a Cyberman, Dalek or J Edgar Hoover. Or, if the good guys get hold of it you can chuck a cloud into a Cyberman's face and instantly restore him to the original person.
My very first DW:AITAS online scenario employed nanotech to 'cure ' Cyberconversion but it ultimately failed because the psychological conditioning would re-assert itself( and anyway in my game it was all a plot by the Cybermen to convert people more easily).
Regarding Osgood's death: We never DID find out what happened to the Zygon that took her form. It might've gone to work for UNIT as well.
True he/she/it also seemed fairly friendly. We can't be sure which Osgood was disintegrated, or even if she was actually disintegrated. An Osgood will be appearing in the new season and there'll be Zygons, leaving several options open.
Osgood is back, fresh from her recent murder at the end of last series. We recently confirmed that Osgood was definitely dead and not returning - but in a show about time travel, anything can happen. The brilliant Ingrid Oliver is back in action. This time though, can the Doctor trust his number one fan?
Time, time,time, see what’s become of me. While I looked around for my possibilities... My AITAS files.
Loved it! Surprisingly dark. Definitely hope Michelle Gomez makes another appearance as The Master. She's probably the best there's been since Delgado. And Clara and The Doctor's goodbyes at the end... perfect. She may not have had as strong a story arc as the Ponds but I reckon she surpassed their ending.
Cyber-brig was a little cheesy, but that's kind of what you expect from Doctor Who. I wonder did he jet off to foil a bank robbery or something and will we see him return as a sort of upper-class English Iron Man
Michelle Gomez is one of the best who has been the master