I was actually thinking about this today. This is brilliant and very easily doable without really changing anything about the board or doing any development.
Yeah - there's no way I'm doing ads for legacy members or treefiddy. If there was a way that wasn't overly manual to do a group with people who have 100 posts within the last year that would get you excluded from ads too. My thing is if you are a pure lurker with no account you see ads, but it shouldn't make the site unusable (that happened this past year and was fixed recently). I've told people this before, but if we had just 8 $750/mo sponsors we'd add even more NIL programs and probably have the Kill Squad done.
The site isn't in danger or running at a loss in a fiscal year that is calendar aligned - if it's August to August aligned there isn't a shortfall. The danger is that if Surly shows a loss for more than 1 year it becomes a "hobby" instead of a "business" from the IRS perspective. If anything we just cut back Burnt Ends and the tailgates and call it a day.