I've noticed the decline. I figure it's probably just a temporary trend. I know that I myself go through phases where I don't bother much with the computer at all, much less programming. But then the bug will bite me again, and I'll be "turned on" for a few months, and sometimes even post here about my projects and ideas.
There definitely has been a decline in developer discussions. Given the complexity of individuals and their daily lives, it's got to be the case that many factors play into this. I predict we'll see developer discussions wax, rather than wane, again, at some point.