This thread has me concerned; I’ve recently purchased plane tickets for two separate trips and I don’t remember seeing any references to a new pricing category. My tickets are on Air Canada and Westjet, although I think the Westjet ones may be a code-share flight actually on Delta. Both those airlines have 3 classes that I know of: Economy, Premium Economy and Business (neither has First on the aircrafts we’re flying).
We always fly economy and pay for seat selection and checked baggage. Even doing so (at approximately $50/pp each way) it’s still less expensive than premium economy. We’ve also taken a number of flights without paying for seat selection and have never had the experience many report of being separated in random middle seats.
ETA: Question for anybody that’s flown on one of these Basic Economy fares - How do they police who is or isn’t putting something in the overhead bin?