AMC's been at it for a year and is still committed to it. Regal's corporate parent has been at it for decades and just expanded it to the US (via Regal), so I assume they have the data to make the numbers work.

Also important to note is that both AMC and Regal subscriptions are twice as much or more per month as MoviePass was...closer to the original/sustainable MoviePass pricing (when it was a lot smaller and not very popular).