Fisher is the only one suitable for and ready to be Captain, IMO. Josi is only just now coming into his own as an elite player and I'm not sure about risking that by throwing the weight of captaincy on his shoulders. Subban probably could be a Captain, but giving the 'C' to someone brand new to the team is very unorthodox. Johansen could perhaps develop as a leader, but he's not there yet and he, too, is very new to the team. I can see one of those (particularly Josi or Subban) getting the 'C' in a year or two, once Fisher is gone, but not at this particular moment, especially with Fisher there as the perfect candidate. It's also just a nice way for the organization to show how much they appreciate Fisher before he hangs them up.