This wouldn't lead to a scarcity of merits(Smerits), even though ordinary members(who aren't M.sources) get banned, go inactive or even decide to keep a firm grip of their Smerits, there are more than enough merit sources with more than enough Smerits to keep the merit system alive and "running"
And to think that merit sources are updated, to a certain degree frequently, if probably one or a few of them go totally inactive or gets banned, they would be replaced.

So actually good posters have nothing to worry about in terms of who's gonna hand out merits to them, the forum has taking good care of that, it's down to you(us) to do our own part(through good, quality posts).