My current methodology for our immediate family is aligned with the common back up advice - one local copy, one off-site copy (at grandma's house,) and one in cloud storage. We're using Google Photos for cloud storage. The easy integration with Nest Hubs makes for nice digital picture frames around the family homes.
What is your system for backing up family photos and videos to stand the test of time? Is it adequate to put everything in cloud storage and forget about it? Do you reassess every couple years and adjust to the new landscape of storage services? Is it unavoidable that we'll be paying $100+/year forever for a [presumably increasing] few terabytes of cloud storage?
Is there a good solution for posterity? For example, once I die, and if my family were to become unable to pay the hosting bill, is there any way to guarantee these heirlooms remain intact and available?