Boeing has always been a fascinating tour for me. It was always amazing to see the 747-400 assembly process. As far as competition goes, niether Embraer nor Bombardier has products that compete directly with the 73 series. They are both still competing with their own products in the commuter segment. The A318 through 321 are direct competition but are largely seen as disposable aircraft. I would keep an eye of China for the emergence of the next true competition in the fastest growing marketplace.
Composites have been flying a long time now in commercial, business and military applications. Once the bugs are worked out, the 787 will be the dreamliner it was supposed to be for Boeing. I wasn't too quick to join the CF bike craze and won't be too quick to climb aboard a 787 either. Let the bugs work their way out first. Boeing has never built a lemon and I don't expect they will in the 787.