The new car market is the only place it matters- the used car market doesn't change manufacturing decisions.
Sadly, I can drive an auto but I know people who can't drive a manual. That means unless a dealership is really sport oriented or wants one stripper on the lot to allow ads saying
"New cars as low as..." then they don't want to stock many (if any) manuals- because a car I'm not thrilled with may still leave with me, but a car my neighbor is incapable of driving isn't going anywhere.
Generally, I'm in a car for a while and the absolute hell of depending on an electronic committee for my gear selection lasts a lot longer than the time spent searching for the right car. So I decide ahead of time what I want instead of just taking what some salesman has on his lot. The internet helps here. The two new cars we've ever bought have been manuals, and I put over 200k on one and am over 80k so far on its replacement, so yeah, the bit of time spent searching has paid off (okay, it paid off on the way home both times
). We've only settled once on an auto, and that was the minivan because they just don't make them and the platform was too useful to not get. See? They made the sale despite the less than optimal transmission.
Long term, I'm hoping to otherwise skip automatics by hanging on to these increasingly rare manuals until I can move over to electrics.