The leagues won’t survive if paywalls go up. Watching your team “for free” via OTA broadcast TV is how they got so big in the first place.
These franchises have local monopolies. There's no substitute, no competition, so there's little risk of "not surviving". Countries that are serious about soccer (EU/LatAm) will have several teams per city and each team will take part in a dozen independent leagues, but if you move to Canada each city has this one Hockey/Soccer team that matters, and the one league that matter is the NHL/MLS.