Let me summarize:
1) someone ask in the mailing list about the future of the ubuntu derivates (even if it is pretty obvious, to me)
2) canonical's devs say that they can help in the process to add Mir compatibility for Kwin/KDE.
3) Someone try to explain that even if someone write the patches for Mir compatibility the problem is not solved because the obvious side effects, that are the followings:
- when you have adopted those patches upstream, the upstream devs must take care of them, no more the canonical's devs.
- because Mir is a canonical solution, how the upstream can check if future development break the Mir compatibility or add regression without properly testing? So the kwin devs must install ubuntu only for check that? LOL
- what happens when ubuntu devs break API/ABI for the needs of unity? The KDE upstream must work for fix their code to be compliant again, because that code are upstream now, and for the only reason to support canonical egoistic solution? Pls don't joke.
4) Marting (in his blog post) put a big problem in the table:No one has replied to that. The only problem of the mailing list's attendee was about the bug report caming from unity patches. LOLMir doesn’t have a real protocol. The “inner core” is described as “protocol-agnostic”. This renders a problem to us if we would want to use it. Our architecture is different (our design of having desktop shell and window manager separated) and we need a protocol between the desktop shell and the compositor. If Mir doesn’t provide that we would need to use our own protocol. And that already exists, it is called “Wayland”. So even if we would support Mir, we would need the Wayland protocol?!? That doesn’t make any sense to me. If we need to run Wayland on top of Mir just to get the features we need, why should we run Mir at all?
5) the kubuntu devs have no technical skill for implement all that changes downstream and the upstream have all the reason to refuse the workload and the responsability to maintain the Mir specific code.
Short story: Still it is Ubuntu/Canonical who is playing a dirty game here because now they try to move the responsibility of this mess on others, and someone (like you) is already fallen in the trap.