I think you shouldn't need to worry about that because more and more I see there are many newbies ranked up to full member ranks, some users also have higher merits than the activities. So the sMerit distribution in this forum is still working, but we can't predict the future, maybe we will see evil sMerit or theymos start to decay someone sMerit from some period of time.
There’s still a lot of merit source that continuously get their merit regularly. I think the only way for smerit exhaustion crisis to happened is when merit sources doesn’t receive their supply merit since the circulating smerit will surely stop circulating at some point since it decreases by 50% when it sent to differ user.
I'm looking forward that we didn't come to this point since it means that there's no constructive post being created for merit source stop sending merits to user.