Nix 3.0 (a.k.a. Nix with Flakes by default) is currently under a feature flag of Nix unstable, so before this feature lands production Nix unstable needs to become the Nix stable, and then the flag needs to be removed. This will take a few releases of Nix, yet

The benefits of it, however, are easy to see at a first glance.
The drawbacks of it are also there,
and some people are willing to pay for the benefits of using Flakes
with the risk associated to using Flakes in the first place.

This milestone will aggregate all the work required for Makes to run on Nix 3.0