Excuse my ignorance of the first two pages of this thread but:
It will have a detrimental effect on his captaincy aspirations. Lockyer is a quality player, and a proven captain. But if Johns keeps his nose clean, and with Lockyer having these comments hanging over his head until the Bulldog's scandal goes away, any suggestions there is any debate about the Australian captaincy can be washed away now.
His joke wasn't in the best of taste, I think most will have found it funny though. The point is that these sort of jokes are not appropriate at a time when an allegation has been made that is yet to be proven. It potentially compromises the validity of the alleged victim's argument if other players are joking about it.
Clearly the apology was always going to come - even if it was Lockyer's idea. The Bulldogs issue isn't going away quickly, and Lockyer will know for next time that Australian humour isn't really appropriate in an open forum that the media see and hear.
I'll go take a holiday now. ;-)