We now have a healthy competition between several JS domain-specific build tools bit.dev, Nx, Turborepo, and Rush. This is in addition to plugins to general purpose monorepo tooling like rules_nodejs (Bazel). I'm looking forward to the seeing the new ideas that come out from the community as this field matures.
However, I feel a bit sad at the state of general purpose build tools (Bazel/Pants/Buck, make, GitHub Actions, Maven, Nix) or cloud-based IDEs (Cloud9, Codespaces). These tools come off as too complex to operate and build on top of such that we, the JS community, seem to be choosing to build JS-specific tooling from scratch instead. There are a huge number of mostly non-JS-specific problems that monorepo tooling eventually needs to solve: distributed build artifact and test result caching, distributed action execution, sandboxing, resource management and queuing, observability, and integration with other CI tools to name a few. I wish somehow we could reorganize around a smaller set of primitives instead of what appears to be reinventing the wheel.
Regardless, I think all of this effort and attention has lent credence to the monorepo thesis, and I'm very excited to see what's next.