A time limit after disasters would be necessary. It’s difficult to think of a proper time limit though, as even a month might not be enough time if your entire house burns down.

and also accounting for low bandwidth connections… whats more, some shitty providers even have monthly data caps

Maybe a payment system could be set up to where, if your server doesn’t ping for a week, your credit card is automatically charged (after pinging you with many emails).

yeah, that would be almost a necessary feature. being able to hold on to the backup when you really can’t restore.