I second that there should be less sub boards until the volume of user generated content warrants doing so. It is a premature optimization to design for an uncertain point in the future. At this early stage, it'd help the growth of this forum by facilitating the best user experience through higher content density and livelier discussions.
Later when you reach the point on which more sub boards are required, it may not be necessary to re-sort the existing posts but archive them in sub boards (e.g., "WSL 1 Posts 2015", "WSL 1 Posts 2016", and so on). Those who intend to locate certain past posts can always use the search feature. Also, the younger users seem to care less about archiving/retrieving content but focus on now (see: Snapchat).