There is a missing piece to all this.  Yes, the C-series is an impressive piece of technology to fall into Airbus' lap, but it is still yesterday's technology (aluminum airframe) in some respects.  In a nutshell, Boeing's Yellowstone roadmap was to develop a true composite aircraft in the 787 and then eventually re-invent its entire fleet in composites.  Boeing deviated from that somewhat in the 737 Max, but may have just been given the kick to get back on track, which could mean a true composite competitor to the C-series, potentially within a decade.