For posterity and "the test of time," I really think you need to create physical photo books. My wife and I have used Blurb for that. It's not cheap, and it's a lot of work, but I'm skeptical that our digital photos will outlive us for very long, for the reasons already mentioned.
I've found that the greatest benefit of cloud storage is not as a backup, but as our primary place to keep and look at photos. We started uploading and organizing everything in Flickr a few years ago, and now we spend more time enjoying our photos with Flickr's web and mobile apps than we ever did when they were scattered across our laptops and backed up to an external hard drive.
I still have the photos stored locally on my laptop and an external hard drive, and I fully expect that I'll need to upload them again to another service (maybe Google Photos, if that still exists) when Flickr finally fails as a business.
I've found that the greatest benefit of cloud storage is not as a backup, but as our primary place to keep and look at photos. We started uploading and organizing everything in Flickr a few years ago, and now we spend more time enjoying our photos with Flickr's web and mobile apps than we ever did when they were scattered across our laptops and backed up to an external hard drive.
I still have the photos stored locally on my laptop and an external hard drive, and I fully expect that I'll need to upload them again to another service (maybe Google Photos, if that still exists) when Flickr finally fails as a business.