I could have included extermination, and I could have been accused of baising the issue even more

Extermination was indeed historically used by states (especially in newly conquered territories) but to me it seems to be a separate solution from deportation or expulsion. Sometimes however deportation was used as a cover for extermination.

That is the extreme of (2). Aparthied-era SA included "independent homelands".

By formulating it as you did originally you imported negative connotations. By picking this particular example you again import negative connotations. Many of these are pretty reasonable. Independence imports positive connotations, many of these are pretty reasonable. But you seem to refuse to accept the latter. Why?

In any case I think there is a big difference between setting up say a Millet system or some other kind of separation in the same state and dissolving the state entirely and have each cultural community be sovereign.

I was assuming that it isnt. You cant' solve the problem of de facto multi-ethnicity by wishing it had never happened.

Isn't this a narrow perspective? Just because this isn't a solution to existing multicultural societies like say the US it doesn't mean it isn't a viable solution for many other societies (such as say Japan or Finland).