I think it will be important to have many civs that have good routes to quite a lot of other civs to keep the switching interesting. If an Indian civ always leads to Indian civ, and Chinese always leads to the next Chinese dynasty, the mechanic and possibilities are wasted. Hence, I think Mughals are great, because they are also a logical follow up for any Persians or Mongols (or a hypothetical Timurid or other central Asian civ). I guess Chola can branch off to SEA easily, and can be chosen from Khmer in vanilla. The biggest mistake, at least from my perspective, would be to allude to a monolithic cultural or regional concept, and allow any purely linear paths that never branch off or can be joined from the side. It would also make the game much, much more boring and repetitive.