DFWRevolution- I'm considering the 2nd generation 737s, the airbii, and the 737NGs as 3 distinct families of a/c. The point is this: When UA
, US, and others were looking for narrowbodies in the early and mid-80s, they couldn't wait around for the airbii to come online. Boeing made a killing for 8 years or so on carriers who needed frames then. Once the airbii came along, a readjustment was necessary and from that the 737NG was born.
Similarly, a carrier looking for a 90 seater now (or, let's say, in 2 years when the bigger Embraers are online) is going to have a fairly easy choice as the E190 series is far superior to the CR9. When the RRJ or the new CRJ (will that be a BRJ?) comes online, things may be change, but Embraer has the market cornered for now. For as long as it takes competitors to develop their new a/c, that means profit for Embraer. After that, who knows?
After all, the rule which you present as hard and fast is not by any means. Your comment about 300 seat widebodies works for that family, but few can argue that the Lockheed benefited from Douglas' 1 year head start in DC-10 production. In fact, I've seen arguments on this board and elsewhere indicating that this delay was a big reason for the DC-10's greater market success despite some obvious bad press (AA 191 et al).