I'm not really sure. They never meet again could mean that Nika and Imu ended up as enemies, while they will sure meet again, could mean that Nika and Imu will became one entiry, in different terms. SO unless Nika and Imu will kill each other, to stop this endless war, that continue threw thousends of years, the Balance between Chaos and Order should be restored.
Maybe NIka destroyed the First World, while Imu lose that battle. In the Second World, it was Imu who won the war against Nika. And now it's the Third World and I'm clearly sure that you can't just Kill Imu or Nika once and for all. So maybe you need to destroy both of them, or reunite them. And if Nika and Mu will be reunited the endless war will finally come to end.