The real question is, is there any "game changing technology progress" with respect to structures and aerodynamics that would really justify a new plane compared to the ATR72 or Q400..
I seriously doubt that.
The real progress is and has been on the engines in the recent years. Just look at the A320Neo, B737MAX, and also C130J.
Putting up to date engines on an "old" airframe obviously still results in a very competitive aicraft.
All the "all composite excitement" seems to have significantly "calmed down", and even an "all new" design as the CSeries doesn't seem to have a "game changing advantage" over the A319NEO even though Bombardier had the chance to integrate latest aerodynamic or structural technology.
So, once comparably advanced new engines are available for this class of turboprops, ATR or Bombardier could right as well retrofit it to their legacy designs.
What's left is to go for an unallocated market niche, i.e. 90 seats.
But the question is then, is there really a market for 90 seat turboprops? And if so, could this be covered by ATR or Bombardier by simply stretching their legacy design one more time and thus by far less cost than SAAB with a completely new design.
Regards,
ihg