As for as "persistence" is concerned I really care only about offline PWAs. Why would a website need offline data after 7 days? It would improve performance, that's true but everything else should be "fresh" unless that said website wants to actually behave like an "app".
Maybe the "website" should ask the client to be installed as "app" if the user wants to take advantage of persistent storage(and other "app" features) . Asking the user to install(which is actually just a kind of bookmarking for PWAs) isn't that much of an effort if the user is planning to use it regularly.
I made one of these. We generally expected users to be offline for at least a week. Probably using the app regularly on their respective devices (but possibly not), and syncing data again when they had a good internet connection. Uses Dexie and React, syncs with a horrible Drupal site. It's always going to be uncertain to rely on a database held at arm's length by the browser, but in practice it worked incredibly well on all manner of devices. I guess it won't anymore. (Thanks, Apple!).
This is absolutely a necessary change on some level, but I think if Apple wasn't in complete control of a web monoculture (and obviously uninterested in anything that doesn't sell more iPads), it would be possible to steer this API towards that without breaking a bunch of peoples' stuff.
