[lanstin]

As long as that N is high enough for each market, it’s good enough. When you are down to 3 producers, well there are reports of tigers there.

[eru]

Yes.

As a small wrinkle: the actual observed number of producers can be small, but the market still be competitive. See https://en.wikipedia.org/wiki/Contestable_market for one case: when potential suppliers are waiting on the sidelines.