Short answer, in my experience is no it doesnt ever end. BUT it becomes obsolete to an extent. In my games by the time i got realm divide declared there was only 6-7 factions left in the game, and as i knew it was coming i had my borders ready to repel any threats. To be honest realm divide just hastens the end of the game, you end up with no choice but to conquer everyone or you run out of money.

The hardest thing do deal with in realm divide is the money loss from trade. In my Mori Camp even with all trade nodes with full Naban fleets on them, I dropped from like 30k income a turn to like -15k a turn :S

but it gets to the point where you are so big and there are so few factions that realm divide does nothing to you. i doubt you could ever get a peaceful end to the campaign tho in those terms.