I wouldn't even call it 'sampling' - even of this forum. But we do have over 80+ people willing to pay in this poll; and I'm just curious how many of them would really do it.
I think you are mistaken about the "all you have left" part; sure, some people left due to the lack of a FF camera (and now are using Canon FF, Nikon FF, Sony FF or m4/3
) - but the user base is not like a static, fixed amount which can only decrease, and would eventually become depleted. There are newcomers, people change (e.g. their income, how they do photography), the market changes (e.g. FF cameras at prices we couldn't dream of before 2012).
It's far from a hopeless situation, it's actually the opposite.