If Johnson can go around another year then I'd continue with him.
You can't or rather shouldn't take the captaincy away from one old timer and give it to another old timer there's no logic in it and in fact will become a slap in the face to Johnson if that scenario unfolds. So if Johnson hands down the captaincy then it is going to go to a young/er player.
Who are the probable chances: Chris Newman, Nathan foley, Brett Delidio and Shane Tuck.
Chris Newman: Has age on his side. he's an average to better than average footballer, is over rated in my opinion and would have good trade value. Can he lead, possibly, could be the making of him. I wouldn't pick him as captain but given the intellect of those in charge I think he is probably the front runner.
Nathan Foley: We depend alot on this player, he's a better player than Newman and can do things on the field that you would expect a captain to do. He is in the unfortunate position of being a further developed midfielder than his younger partners. I believe the biggest stumbling block that Foley has to becomming the captain is not himself or the percieved inability to shake a tag but the coaches box. I believe the coaches box will be so god damn scared of overloading there already pressured best midfielder with the burdon of captaincy. Could be a good choice, will lead from the front and given good coaching his fellow midfielders should catch up releasing some of the pressure.
Brett Delidio: Comming along nicely but if the article I read in the age by Caroline Wilson is any indication then this boy isn't ready to be the Captain of our club just yet, he's still two years away. Leave him alone and let him develop more. As a side note, If Richmond believe that they have to offer Brett the captaincy just to keep him at Richmond then they are better off letting him go, you can't buy passion.
Shane Tuck: Interesting proposition, only because he is a consistently good player, but wont cut it as captain.
What should happen:
Leave Kane Johnson as captain and give everybody another year of development, it isn't going to hurt anybody and isn't going to make any massive difference to our performance next year. Kane doesn't have to play every game and foley, newman and co can share the responsibilities around on those occassions.