I agree with that, I think Kirkman loved the idea of having all these communities, but in practice he couldn't give characters the required time for us to give a damn. I see all out war as a culling of the unnecessary, so we have a core group of characters with potential for further stories, and that we actually care about seeing.
I see the main group after all out war being:
Rick, Carl, Andrea, Maggie, Sophia, Jesus, Ezekiel, Aaron, Heath, The Euge and Dwight
Plus a few of the 'good' Saviors and whoever this new group is.