i guess the title is actually two CK2 questions.
1) Will there be a rota system?
Or at least something that sees Kiev pass between the various branches of the Ryurikovich dynasty?
(as a default, barring countermeasures by the AI, player, complete randomness, etc.)
2) Will there be a Kievan Rus'?
Or just umpteen unrelated principalities that never get around to waging internecine succession wars?
And possibly a third.
3) Have you considered how foreign interventions might be used as a means to back rival claimants?
External allies were often used drawn in.
e.g. Poland might back the prince of Vladimir-Volynsky, Varangians via Novgorod, Pechenegs the prince from Pereyaslavl’, Cumans the Chernigov candidate, Bulgars the one from Suzdal’, etc cetera.
i'm sure it would apply to other situations. Like the French backing a pretender to the English throne from across the channel. Or the Kingdom of Naples restoring the Papacy in Rome after pesky republicans take over there. Something like an "expeditionary force" that doesn't draw two neighbours into a realm-wide war because one dynasty backs another. (To return to the first example, say... the King of Poland putting his daughter's husband back in charge of Kiev after the son-in-law being booted out by the Prince of Polotsk.)
In CK1 it seems the relations between the Rus' principalities either collapsed into a short-lived chequerboard or one prince gobbled everything up and became king. Whereas i'm wondering if it might be possible to have the default settings lean more towards a coherent, unified Rus'.... that also happens to have a long string of violently pointless disagreements over who is next in line. At least until the Mongols show up and vassalize them for failing to switch to Imperial Prerogative and Agnatic Primogeniture.