There can't be anymore reincarnations past Naruto and Sasuke and there cannot be two Ashura reincarnations living at the same time (in normal circumstances).
The feud has ended (for the time being), but seeing as their chakra/souls have gone on transmigrating for the last 900 years, there's no reason for them to stop. BZ implied that reincarnations have managed a sort of union before anyway.