Frankly, once Voyager was up and going, it was surely just a matter of time before some such announcement would be forthcoming. For Cessnapete, I can't see why dealing with Royal and Ministerial flights should be beyond today's cabin crew. In days of yore, 10 Squadron and 216 Squadron crews with the requisite categories mixed VIP and other MOD tasking work as a matter of course. The role fit and the rapidity (or otherwise) with which it might be changed will be an interesting issue to follow. Role changes were an everyday part of the VC10 years, but I imagine that the ability to change with Voyager will be very much subject to Contract amendment.
Oh - and if it's to be 10/101 Sqn crews flying VVIP tasks, rather than AirTanker crews, might they do so in blue/KD?