I don't know about this "losing marketshare" thesis.
I'm not sure that people will really be cancelling for other services. Disney and the rest will really have to nail their interfaces, algorithms, and selections to get people to think "this is the best and I don't need that other one anymore."
I've been meaning to cancel my audible and crunchyroll subscriptions for like a year, but I never get around to it, because it's just too convenient. And I'm a cheap bastard, imagine what the average consumer who doesn't mind carrying a credit card balance does.