Is there still demand for 32 bit apps? The last 32-bit mac was released in 2006 and the last OS 32 bit OS in 2009?
I've assumed anybody with a almost 10 year old computer doesn't get that much new software. I tend to release supporting the last 2 or 3 OS releases and 64-bit only and haven't received any complaints.
However, you are right, there is little demand for 32bit software; my newer apps require 64bit. But I see no reason to cut off support in an old product.