Once all the backwards-compatible work is done, say in Go 1.20, then we can make the backwards-incompatible changes in Go 2.0. If there turn out to be no backwards-incompatible changes, maybe we just declare that Go 1.20 is Go 2.0. Either way, at that point we will transition from working on the Go 1.X release sequence to working on the Go 2.X sequence, perhaps with an extended support window for the final Go 1.X release.