Your comment is ironic given the comment that you started with.

I am speaking from the perspective of improving HN, so I'm startled (should I be?) to find that the first reply is an admitting that the community will eventually split apart.

From my experience (which was as a developer of a browser game) this is not true. People who complain are people who care. And people who care will stay. People who really want to go will not complain. They will stop contributing and go without much fanfare.

In the end you stay with all the complainers, but none of the non-complainers. This is a real risk for a community. (In the case of the game it was 'simple' to fix this: change the game. It is far harder for something like HN)