Aye - I would never have thought Noland would have done a war film, but I guess it makes sense really.
I could see this being Nolan's big oscar push - a pretty straightforward story told in an interesting and life-like way. The trailer has the ticking time clock, so he'll probably play with time again somehow; probably with different story arcs going on at the same time, but told from differing perspectives.
Considering The Prestige's use of secrecy and sacrifice, he could easily play with some kind of dual-plot device. Also, he could rely heavily on opposing forces chain of command and dissemination of information or propaganda - akin to The Presige.
I don't know too much about Dunkirk, but weren't there some kind of standoff to let the British Army retreat?