Version exclusives are a mainstay in all Pokémon games and have always been one of the catalysts for getting players into trading or perhaps even going so far as to purchase both paired games.
It should be noted that the Japanese versions of Gold and Silver had the Teddiursa/Phanpy families in the opposite game as they appeared in American versions of the games. At this point we know that those family's appearance stay true to the original Japanese G/S games but we do not know if those families of Pokémon will remain the same (stay as they are currently) or change (and continue to remain in the same games as they were in the American G/S games).
Some may believe that Teddiursa/Phanpy have moved, when actuality they just remain in their true version as far as the Japanese games are concerned. It is possible these positions will remain the same as, when Red/Blue were remade for America, Blue was changed to Green with respect to Japan's naming of the first paired games.