411A - I think the RJ market could have supported a third aircraft manufacturer. If you look at the BA (Business Aviation) sector there's fierce competion between Gulfstream, Dassault, Bombardier, and Cessna, and those companies are doing well so far. All of them -except Cessna- are testing or developing new types. The most intensive sales battleground seems to be the mid-range to long range aircraft section.
Now, the RJ section only has two players:
Canada vs. Brazil!