Out of curiosity, I sampled this site's statistics (shown at the top of the page) at intervals for the last 9 months:
2016.11.16 Members: 80,004 Posts: 1,827,628
2017.02.15 Members: 80,661 Posts: 1,859,382
2017.03.23 Members: 81,001 Posts: 1,873,638
2017.04.05 Members: 81,113 Posts: 1,876,020
2017.07.05 Members: 81,729 Posts: 1,908,065
2017.07.27 Members: 81,896 Posts: 1,914,419
The total membership count includes a large number of inactive members. I haven't plotted it, but my rough estimation is that it shows linear growth. Alas, the number of paying subscribers -- a critical element -- is not shown. I'm sure Sean has even more detailed statistics.
But the point is this, APUG/Photrio is going to need paying subscribers (as well as advertisers) to survive. I think many people here were truly shocked to learn the subscription rate was about 1% and dwindling.
I know a few other non-photo sites have resorted to restrictions on non-paying members, with enticements to pay, and it's always a nasty subject. Sometimes it fails.