Originally posted by normhead Waning K-mount support.... pfffft
Support is waning because they can't sell the lenses. Despite the great lenses made by Sigma, they clearly aren't what Pentax users want. How is them stopping making lenses Pentax users aren't buying a problem? You're out of touch with the Pentax community.
Every time Sigma stops making a lens, it's because there is something more popular out there. Pentax - think light weight and portable. Sigma- think big and bulky.
Sigma - think competitive company. The less they sell, the more its a sign Pentax is meeting the needs of their customers in house.
[... snipped for brevity]
Your hypothesis is one possibility why Sigma doesn't have more K-mount lenses. An alternate hypothesis is that the K-mount market isn't large enough for Sigma. I don't think data is publicly available to know which one is correct. The truth might lie somewhere in the middle.
Canon is the most common mount around so that's where Sigma makes the most profit. The quality of Canon lenses affects Sigma's total volume, but even if Canon makes great lenses that satisfy almost everyone, the scraps are still highly profitable for Sigma.