I don't think cord-cutting is going to be a problem in the near or even medium term. A la carte, in the form of the sports-free packages some cable companies are already starting to offer, will get them long before that, even if the cable companies are successful in the short term at fending off actual a la carte.
If the distribution of ESPN or FS1 dips below, let's say 60%, it's going to be difficult for big-time teams and leagues to continue to justify treating either one as "good enough" for the biggest events either network has. I don't think most teams and leagues will be willing to settle for being on a premium channel or pay-per-view, or you'd see a lot more sports on HBO or Showtime. No sport wants to go down the road boxing took. That'll cause a feedback loop where the decline in major sports on ESPN lowers the value of the sports package, so more people leave and/or ESPN has less money to throw around.
I actually think sports could be a cause of cord-cutting; if teams and leagues make a full-scale return to broadcast, it becomes a lot easier for sports fans to cut the cord, and right now sports might be the single biggest obstacle to it.