What everyone seems to be overlooking is that currently, perhaps for the first time in history, the airline industry is actually making money. Even with airlines cutting back service, benefits, space and adding all sorts of extra charges and fees, pretty much every airline in North America has been packing their planes and making money. It doesn't seem a stretch that there could be enough excess demand to satisfy a new airline with modest ambitions.
Moreover, I think the catchment area for YHM contains a lot more people than, say, even YVR. Yes it's a given that the small number of flights to/from YHM will be a limiting factor, but if they are careful and selective they might make a go of it.
I don't know if it's a good idea or if they will be successful, but all of the comparisons made so far refer to a time long ago. The airline industry today is not what it was 20 years ago, or 10, or even 5. It's not even the industry it was 2 years ago.