I like this updated roadmap. We just merged yet another 2.6.1 fix so please keep using and testing 2.6.0 to find whatever remaining quirks there are so we can get them cleaned up.
When it comes to 3.0.0, I think the C++17-ification changes are almost done. Certainly there are no more big C++17 features to use. The remaining language usage upgrades are minor and/or can be done after 3.0.0 ships if need be.
As for API-breaking changes, those are harder to predict but I'd like to think most API changes are also done although some of the remaining API changes planned are pretty tough to write and test so don't expect them to get completed soon. My personal goal is to tentatively finish all these API breaks by the end of 2023 so we have time to let the API sit in a stable state while the final testing push occurs.
I expect we need on the order of >3 months of a stable API to be certain that what've written can withstand the test of time. I'm not sure where the other maintainers are at, but I'd like to ship 3.0.0 in the first few months of '24, hopefully soon enough to get it shipped into Ubuntu 24 LTS but that may be tough if we can't freeze the API by approximately November of this year.
