I would love to see a Warband style game becoming a e-sport but realistically I can't see how M:BG has any chance at becoming one.
It doesn't have the potential to pull in a massive amount of players, even IF the game will be good, especially with more M&B style games being released these days. It doesn't have a big company like for example Riot or Valve behind it who could fund the competitive scene, I can't see a way to pull in any sponsors. I just don't see how it has anything going for it in regards to becoming a e-sport at all even though I really want to. It might have a small competitive community around it like native but that's about it.
Also, having 8v8 or 10v10 teams be the competitive standard would be a problem for any game trying to become a e-sport.