Standalone vaults (including 3rd party sync) will not be part of 1Password 8. You can read more about this here: https://1password.community/discussion/comment/602340/#Comme...
(full disclosure: I also know the developer personally and have watched as he evolved the product, and since it has comprehensive import/export features I know I can get my data in and out of it safely - and without being beholden to a subscription that adds effectively zero value)
It's a shame, really, I've been using 1Password forever and have kept at version 6 precisely because I want to limit my data exposure and have a bloat-free experience.
Goodbye, and thank you for all the fish.