The most thoughtful solution was one proposed by Greg Johnson. It's known as "the slow cleanse." Various people have picked up on it and made YouTube videos etc. but here is the original article:

Counter Currents:

Thus to persuade people to actually build ethnostates, I have to deal with four questions: Is ethnic cleansing possible? Can we live with it? Is it moral? Does it have to be icky?

Is it possible for millions of non-whites to leave white nations? I always answer this question with another question: Was it possible for them to come here? If it was possible for them to come, it is possible for them to leave, with all their children as well. With modern technology, it has never been easier for millions of people to move. Moreover, people are more rootless than ever. The average family today moves every few years. So most non-whites are moving anyway. We just want their next move to be outside of our homelands. So there is definitely a way to decolonize white homelands. We just need to have the will. [Cont...]

As stated finding the political will is the difficult part — this thread explains exactly how difficult — but things can change surprisingly quickly.

cc: u/Tuisto