One of the nice things about the way things are now, is that the diversity of companies and pilot groups can let each of us find a company that is the best fit for us. A single contract would be born out of an immense poo flinging contest, as tens of thousands tried to get what they consider to be the "best" parts of their current work rules implemented. We'd end up with work rules that everyone hated.

Plus, the companies themselves wouldn't stand for it because they all have different hiring priorities. My spirit interview was a 4-5 hour personality driven reality show and they wash out posers in training. Delta went on and on about my high school grades, spent less than 5 minutes discussing flying qualifications and experience, and hated me so much they didn't even offer a do-over. Southwest was a couple of hours talking about flying with a guy who had more flight time than I'll ever have, before I was even born. My friends flying Cargo sitting reserve make more than I do in my best month and can't believe I willingly put up with PAX issues. Completely different hiring priorities, and pilots have a chance to find a pilot group, company, and contract that fits their personality and work/lifestyle preferences. That would all vanish with a single contract and national seniority list.