We'll see how Apples interface will look like. With a centralized marketplace like this they have a perfect opportunity to build interfaces to work against this, the question is if they will. (e.g. nice overviews, options for time-limits, notifications for not-used subscriptions, ...)
Yes, this is something where Apple's own interests and the customer's might be aligned.
Even just having a central place to cancel subscriptions is significantly better than having to do it individually -- and Apple almost certainly won't allow developers to get too obnoxious with the 'customer retention' hoops we need to jump through to actually cancel.
