Subway kind of locked themselves in the school/business “lunch crowd” for $5 dollar footlongs.
Well Subway was never going to be much more than a low end sandwich shop and not a great one at that. In terms of quality they get beat by nearly everyone else (Debella’s, Firehouse Subs etc), but they are ubiquitous and cheap so they will continue to exist.
They are basically the McD’s of the sandwich chains.