The Google Photos interface itself isn't that big of a product (I think), if you can lose some of the sharing features, I guess it'd be quite an easy app to make that can be run off a v-server or Amazon at considerably less long-term trouble. The big big issue is the seamless auto-upload from phone to Google Photos, that's the fantastic feature that locked me in.

the long term cost of buying something like a 12TB USB3.0 external hard drive and periodically letting it synchronize from your master copies, then unplugging it and storing it at a trusted family member's house is a great deal less than paying for 12TB+ of "cloud" storage indefinitely forever.