The Vari-X III was replaced by the VX-III.
Leupold has announced that they are going to be ending production of the VX-III. It will be replaced by a soon to be announced new version.
I think this announcement will take place at the SHOT show.
If I remember correctly, the difference is in the coating of the optics. The VX-III has better coatings. The current VX-II is what the Vari-X III was, except for the "range finding" ability of the Vari-X III or VX-III.