Historically Epeiros did lose Phyrrhos in the midst of an important campaign - and that didn't mean the end of Epeiros. Mind you, Epeiros turns out to be another city/tribal confederation and being king of Epeiros is surprisingly similar to being the Kunningaz of the Sweboz - at least if I understood Kos' description correctly.
Pahlava was kinda feudalistic if memory serves. Therefore the most powerful clan could largely do as it saw fit. And while all clans were de jure all united under the banner of "The Pahlava" (and would act as such when faced with foreign invasions) in every day matters they were de facto rather like a loose federation. A permanent KH of sorts.
To my understanding: with confederation-style factions and with factions such as the successors this kind of thing (loyalty) is based on the leading tribe/clan and the loyalty of the truly powerful rather than on the distance to leader. Distance to capital makes probably even less sense in this respect- as long as there is a clear dominant political & military factor in the internal workings of the faction and that factor is loyal to the current ruler; the ruler is pretty much safe from dissertion. And if there isn't any such factor the ruler simply isn't safe and dissertion will hapen regardless of where the ruler is located.
EDIT: To say there wouldn't have been any effects at all is probably not exactly true either. But to mod this in...
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