Why not let this list develope to meet the needs of the subscribers.
I havent notice discussion of the standards generates all that much mail.
In fact other topics seem to generate more of the mail than the standards do and in many cases they are interesting and timely.
I think this list would die a slow death if were opened only to discussion of the standards. As long as there is room I say leave it open as a place where Math topics can be discussed. If it starts to look like the discussions of standards is somehow being disrupted by other topics than I would reconsider but I havent noticed it happening so far.