For Spock to become Captain this will depend on Distant Worlds Universe and whether at some stage of the game you get a message that Kirk has been killed.

If this happens then Spock would certainly be the next in line to take over the center chair. If Spock is not on the Enterprise yet then either Scotty or Sulu would become Captain instead of Spock.

The role play portion of this mod will never put Kirk in a situation where he dies.... however if Kirk performs badly or is court martialed then it is foreseeable that Spock, Scotty or Sulu will become Captain of the Enterprise.

Mr Spock
Captain Kirk