All it takes is few bunch of big accounts let the world know they are moving to alternative relays including their own. You can also run your own private or public relays (this is the ideal scenarios where more and more people decide to mount their relays and people share usage between them.

There's a lot of redundancy/optionality here. I for example using 9 relays relays some of them payed some of them my own and one or two public.