Similar to Single-page applications (SPA), single-table application (STA) might become a thing. Just a shard a table on multiple keys and serve the shards as static files, provided that the data is Ok to share, similar to sharing static html content.
do you mean single database? it'd be quite hard if not impossible to make applications using a single table (no relations). reddit did it though, they have a huge table of "things" iirc.
[The Baked Data architectural pattern](https://simonwillison.net/2021/Jul/28/baked-data/)