I think the ONLY reason Zeiss needs to update their lenses is for the new, high MP sensors. Well, their 50mm can be refreshed. But their 35mm and 85mm are fantastic for anything less than 30MP.
For fashion and portrait work, it's hard to beat Zeiss. I hope they have two different lines for the immediate future. Until I get a camera above 30MP and A LOT more paid work, there is no reason for me to get these uber-lenses.