Exactly, so as it currently stands the subscriber tag provides data that the API can in no way provide. What may or may not happen to the API in the future is not important to the matter at hand.
Twitch is not going to supply what a ‘regular’ is because that’s totally subjective and what one streamer considers a regular may not be considered a regular to others. It’s up to the broadcaster to determine what a ‘regular’ is to them. Regardless of what a ‘regular’ is, again a follower tag doesn’t impact that at all. It’s entirely possible for someone to be a follower without ever having seen a single second of the stream, or even visited the channel!
No one is requesting that though. Hypotheticals don’t help your cause when you lack any sort of thought out use case or evidence to show that such a use case is in demand.
You keep bringing up these sort of users. How does a follows tag help them?