I love kingmaker, and I am also sick to death of 3.5 in all of its forms. Upgrading it to the new edition is probably the only way to get me to buy for Pathfinder products. It should basically be its own campaign setting, and get a fraction of the attention that's lavished on Cheliax.
I think there should be more ways for the P2E & DD5E communities to cross-pollinate as well, so this is a good idea.
They can clean up a lot of the plotting problems in adaptation, especially how all the actual kingdom management is more or less abandoned toward the end of the path in favor of conflict with a big bad nobody's interested in. More involvement with the rest of the kingdoms would add links to other areas so people can explore more.
A Pathfinder 2nd Ed discussion which gradually devolves into a Godwin's Law poster child comes up about once a month...you can cover all the main rhetorical points without delay by searching the message boards. All the hate, none of the wait.