Are Series 9 filters on the way out?
 

I've been buying Series 9 filters for a Century sunshade I own. I like the size, weight, price and convenience of these filters compared to 4x4 filters, and I'm kind of surprised that they aren't more popular. But I'm beginning to wonder if I'm investing too much money in a format that may be dying out. It seems to be a bit harder to find Series 9 filters and accessories these days, and I would hate to be in a situation 10 years from now where I can't find accessories and it would cost me thousands of dollars to switch to bigger filters. What do people think? Am I worrying too much about this?

FVESCO in Denver always seems to have Series 9 filters in stock when I need one. I haven't noticed any disappearance of them; but you won't see much mention of them in DV circles because most people don't know about them if they haven't been involved with professional cameras. I still prefer them over using a matte box, but if I need to put on more than 2 filters a matte box is better because I'll get some vignetting at wide angles.