What many don't seem to realize or consider is how carriers like AC are slowly starting to reclaim the regional flying they surrendered to create the regional airlines back in the mid-80s now that they have an aircraft that can actually fill the bill. It's easy to see a C series flying CYYZ-KIAH, CYUL-KDFW or CYHZ-CYVR.
How about Montreal to London City? When that ball gets rolling the 'express' carriers will be much smaller than they are today.
Some carriers like WJ failed to envision C Series market and potential. They will continue to fly Canadians or north Americans via big hubs, through hassle of two-three intentional airports, even for a simple domestic flight. As example, most of the eastern flights (Montreal, Ottawa, Quebec) are via CYYZ to destinations US or Caribbean, just to fill the preferred wide bodies. On the other hand, C Series will be able to operate from medium size airports(Q400s airfields), from far north to a small Caribbean island, between US City Centres or European City Centres, direct cost effective flights, a business jet capability for a regular carrier price.
This is the future:
https://youtu.be/3HtxFg1hSC8