See this new announcement at the official website:-
http://www.cosina.co.jp/seihin/voigt/english/dispo.html
Quoted,
"Discontinue Announcement
We would like to announce that following products are discontinued.
COLOR-HELIAR 75mm F2.5 Black
COLOR-SKOPAR 20mm F3.5 SLII KA
ULTRON 40mm F2 SLII KA
NOKTON 58mm F1.4 SLII KA
APO-LANTHAR 90mm F3.5 SLII KA
ULTRA WIDE HELIAR 12mm F5.6 Aspherical"
It seems that it is solely a commercial decision based on the market demand and revenue after all. :-(
So, will Cosina do the same to their ZK line of the Zeiss lenses next (as it has been rumoured)?? :-o