ETA For 5.x (Diamond Storage)?

I've heard there are plans for version 5.x using https://medium.com/@mudgen/new-storage-layout-for-proxy-contracts-and-diamonds-98d01d0eadb .

As someone who is eagerly await this, is there any kind of rough timeline?

Sorry, there is no ETA. 5.x will come when Solidity 0.9 comes out, and there is no ETA for that either.

Interesting, thanks!

Curious though, is there any particular reason that OZ releases are tied to specific Solidity releases?

In the case of major releases (4.x -> 5.x), we tie it to Solidity breaking releases (0.8 -> 0.9) to reduce the number of breaking changes and migrations that users have to do.