Most of the stickies haven't been posted on for ages. Three years in some cases.
Why not just remove the sticky status and let them naturally disappear the same as other posts as a result of not collecting comments.
We don't have that many active threads as it is but the first thing potential members see in opening up the individual forums are bolded or highlighted threads, that in other forums indicate activity.
But if they've had no posts for that long than the impression created is that the forum is even less active than it is.
And when there are too many, you have to go further down the page than would otherwise be necessary.
Even on days when there are three threads with comments they are further down the page and not immediately noticeable.