I don't think this is a correct take, because most plugins that interact with the database already use the abstraction functions, eg get/set_option(), WP_Query, get_post_meta() and so on.
2. Plugins that do direct queries against the standard database schema (broadly either for invalid (bad code) or performance (valid but slim use case) reasons)
Also, WordPress would of course keep the old query functions around and they would likely add a tag to the plugin repository so authors can mark plugins as supporting thes new ORM features.
These would all work out of the box.
The only plugins that would not work are:
1. Plugins that register their own database tables (however there already exists prior art such as https://github.com/aaemnnosttv/wp-sqlite-db for handling these cases)
2. Plugins that do direct queries against the standard database schema (broadly either for invalid (bad code) or performance (valid but slim use case) reasons)
Also, WordPress would of course keep the old query functions around and they would likely add a tag to the plugin repository so authors can mark plugins as supporting thes new ORM features.
Great idea in my opinion!