This is guaranteed false.
Unless the ‘cheaper store’ has almost all of the customers, you will need to support most of the stores, otherwise you’ll simply lose access to customers.
Just to break even, developers will be forced to support multiple stores.
If consumers want a cheaper option, there is nothing stopping them from buying a cheap android phone today.
That is one extra option for the consumer to choose, if they want it.
It wouldn’t be voluntary. They would be forced to support the other stores or lose revenue.
Claiming it’s just a matter of choice for developers is simply not correct.
The extra options would also come at a cost for consumers who would need to deal with multiple stores, many of them with undesirable features such as weaker privacy protections.
It means lower prices for those who are smart enough to use the cheaper store and those who cannot will stay on the official store that takes its 30% cut.
In fact even the bare existence of other stores would mean that the cut probably goes down, since Apple probably will prefer to stop the outflow of users.
If someone is inept to use other store than the official apple store, then I guess they have to pay the higher price. Your post sounds comical on a forum called "hacker news". You sound as if using a second app store is some secret knowledge...
You also seem to ignore the fact that even computer inept people try to reduce the amount of money they pay for stuff and money is a big incentive (app costs 1 dollar less on other store is a great motivator to learn how to use it).