The Cochrane move to C16 was a plan devised by the Cochrane department. Their radio guy shared with me a number of reasons for the move, including no longer having to rely on the aging infrastructure at the Big Hill tower (which links all the UHF Rockyview comms such as Redwood, Madden, Irricana, Langdon, etc to Calgary), as well as lessening the number of channels the dispatcher has to listen to. As well, it serves to offer a level of interoperability to Cochrane, as they are now on the same channel, essentially, as their adjacent counterparts (Springbank etc).
Cochrane is actually still on their 400MHz frequencies; there is a hardware patch between that channel and C16, made at the Cochrane radio tower site at the top of the Cochrane hill. Let me see if I have the frequencies handy.
424.1625 100.0 PL Cochrane C16 Link
422.9250 151.4 PL Redwood C16 Link
Those two channels are linked together and also to C16. The 424MHz frequency is on the Cochrane hill and the 422MHz frequency is at Redwood's firehall.
Anyway, this is all a roundabout way of saying I doubt Airdrie will be moving off their existing VHF comms any time soon.