Originally Posted by
AVR4000
A logical step for the CSeries as an "A210" and "A230" would be to commonize the flightdeck with an upgraded A320neo Plus in order to bring it in line with the A350 and to provide common type rating between the families.
Commonality is an excellent solution and there are no good reasons *not* to do it (especially not if it ends up with one manufacturer, different flight control systems such as mechanical on some models, FBW on others, different layouts on the flightdeck, different engine manufacturers and different maintenance procedures and so on and so forth).
There is one big one and it's called money. The cost of modification to the Airbus family standard would I imagine be quite close the cost of a completely new design. Not to mention it would the existing customers would not be able to order additional airframes a decade later, unless Airbus would continue to offer both CSeries and "A200" at the same time, which would probably drive the costs for Airbus even higher.
I give less than 5% chance of CSeries being developed into an Airbus family-compatible aircraft any time soon.