1. Storage for 50MB is less than $0.001 per month. So, even if you're storing and backing up every every version of an app, and they update a very high 50 times per year, and they're storing on 12 different locales, that's less than $1 per year for the typical app.
2. "Global distribution" is a one time cost per app update at approximately $0.006 per 50MB per server. For 12 updates per year spread across 12 servers, that's less than $1 per year total. Over 75% of apps are updated less than once per month.
3. Retries, re-downloads and updates are already insignificant transfer costs, per my original comment. Even if you want to attribute 90% of those downloads to being updates from the same set of users, and keep the lifetime revenue per user at a very low estimate of $1, Apple is still taking $6,000 for approximately $105 of hosting costs.
All in all, that matches my original estimate of $100 per 200k downloads for transfer and $5 for server fees. So, as I said, hosting isn't relevant to the conversation, at all.
We're looking at cents per app per user in lifetime costs.
The "Cloud" is disgustingly expensive at nearly any scale. It does require some capital investment and competent people to host your own however. Although there really is no alternative to the cloud if you are small scale but need presence globally.