I was reading the first post in the fan fiction story linked above and it occured to me that if the Romulans did eventually unite with the remaining Vulcans then, depending on when they might have done this, they might not have attacked the Klingon colony at Narendra III, meaning Worf and kurn would still be with there parents and Worf would never likely join Starfleet but serve in the Empire instead, much like the events seen of Mirror Worf in the DS9 Mirror episodes and the alternate timeline seen in Yeasterdays Enterprise.
Well, probably different than Yesterday's Enterprise. If the Romulans don't attack Narenra III, then the Enterprise C would not have to respond to its distress signal. The Enterprise C would not then get sucked into a temporal rift, making it look like they cut and ran, not leading to a 20 year war between the Klingons and the Federation.
If anything, peace between the Klingons and the Federation would still occur, maybe not with the Klingons showing the same level of trust because there was no heroic sacrifice by the Enterpise C.