Like others have said, I don't think he will return to the game. It would be nice if he were to return and give a few updates, but it seems like it's not going to happen.
I don't think this game and community is falling apart as you say. Even though it hasn't been updated in a couple of years, it doesn't mean that it's all going to fall apart and be done with. Kovu may not be here to update the game and make it more fun for everyone, but it's up to us the members to do best with what we got. We can make the game better for ourselves by making presets, maps, items, textures,and other add-ons.
I honestly think trying to persuade Kovu to come back isn't going to get you anywhere. As Feareh said, he didn't return at the request of the staff members of the game. If he didn't come back at their request, what makes you think he will come back at yours? It's a waste of time. Why waste your time when you can be playing with what you got?