I don't think it's Burberry mainline. They're opening up stand alone stores for the other concepts, right? So perhaps there's going to be much more of an emphasis on the other ranges this coming season, with totally seperate campaigns for them.
The SS10 Prorsum campaign was being shot weeks ago. I've posted before, and obviously I am aware that it's not exactly a written/quoted source, but I asked Christopher himself back in October if Emma was returning and he said yes. When I met him he specifically said all the prep was being done for the shoot and it was being shot very soon. Like I said, that was back in October, so even if it's not Emma, I think Prorsum was done and dusted some time ago.