I think it's very similar to sports like Basketball or Tennis. You will absolutely get solid B tiers where fighters can make a living, but people only tend to want to watch so much televised sport a week. The UFC provides 5 or 6 hours of live MMA a week (more on DWCS weeks) which will satiate most people's desire for televised MMA.
Of course there's people going to live shows, which is where I think the regional leagues can make money.
I edited in a bit more detail in my other posts.
Yes, you are correct but you're still assuming the demand for it is static and that the UFC's relatively low quality fight night shows can meet the demand of a future audience.
The Fight Night shows are not well promoted at all and we're at a point where even regular watchers of the UFC do not know who are on those cards. The UFC doesn't have the man power to make those shows feel important. What is going to happen if the sport explodes to comparable popularity in Indonesia or Nigeria? You're greatly overestimating how hard it would be to promote those shows to those markets.
Tennis has different promoters and has 4 major events of roughly equal importance, in 4 different countries in 3 different continents. That is way different from how basketball at its highest level works (the NBA). Tennis and MMA have a lot more in common and Tennis is not ran by one promotion.
MMA I also think is special because fundamentally at its root it
has to be international. It's viable for countries all over the world to generate top tier MMA talent relatively quickly (we've already seen that just with a little bit of commercial exposure a bunch of fighters are coming out of places unknown where before almost every fighter worth a salt was from 3-4 countries). That makes it really different from how basketball has developed.
To use wrestling as an analogy as UFC is based largely off of how wrestling promotions work. There was a point when Wrestling = WWF. WWE was only doing a 3.0 for a while. WCW is bought out by Ted Turner and given a huge budget as well as the resources of major broadcasting of its era (cable TV).
WWE and WCW did not split that "3.0". What happened was WCW and WWE both had 5.0s. They both grew their own markets. When WCW collapsed the WWE didn't start putting out 10s on the ratings. What happened was that some people simply stopped watching wrestling since they were WCW fans not just wrestling fans.
IE, people did not think there was enough demand to feed that many hours of wrestling in a month. But a brand new product grew the market share. People then thought that naturally WWE would cannibalize WCW's market share when it went out of business but those consumers simply went onto other hobbies. This is all just within the domestic market of USA and Canada.
It's very possible that world wide we can get something that is at least marginally popular. Pepsi isn't as popular as Coke but it isn't chop liver. We're not at a point where the UFC is so impossibly big that the idea of there being a second org is out there.
Much, much, much bigger companies have came and gone than the UFC.