We won't know till they release viewership metrics in 2021, at which point subscriptions in HBO Max could have risen or fallen due to a variety of other factors.
I think the Mandalorian comparison is apt for different reasons. Like Disney+, HBO Max only has a robust library of content to its name and one big ticket item (Mandalorian, Snyder JL), but not much else. Of course, there's a vibrant list of future content planned for each service, but they're too far in advance for the service to feel worthwhile in the present.