It's actually possible to do this. There's a thing which is called perpetual bonds, i.e. bonds which pay a fixed sum ad infinitum. Not surprisingly, they have a non infinite cost. (https://en.wikipedia.org/wiki/Perpetual_bond)

If you add a perpetual bonds with a coupon equal to the service charge, and the service price doesn't increase, you could create a perpetual "free" iCloud offering. However, I think the main problem there aren't that many people who are willing to pay for it.