^ I don't see any reason to assume that the final product of this episode is a "third" timeline. I see it as a predestination paradox - it was always supposed to happen.
Meaning: There was never a timeline in which the Enterprise
-C did not respond to the distress call and come to the Klingons' aid at Narendra III. The timeline in which the Ent-C vanished and ended up in the "war future" was necessary in order for the "real" timeline (no war) to happen.
Remember, the anomaly which caused the time travel originated during the original battle between the Ent-C and the Romulans. There was never a timeline which did not have the anomaly. So there was not, for example, a timeline where the Ent-C showed up, battled the Romulans, and was destroyed, but no time travel occurred. Am I clear?