It makes sense from a certain point of view. I mean, if blizzard wanna charge for every patch released they're gonna need to change their monetization structure. But I find it hard to believe that they're not going to make expansions again. The only way this can work is if Blizzard adds a new zone with +2 extra levels at some point, otherwise, the numbers will become bonkers after 4-5 Seasons.
But I hope this leak is not true, because this could very well be a make-up to cover a glorified "maintenance mode".