Given their reputation, I wouldn't have expected some kind of business problem! (It can happen in unusual ways, though. Several years back, we had one here in NM that closed because of its bad sewer system.) But I suspect that this may be more of something along the usual lines: We get older; we want to retire; and we just don't want to do the business dance any more. Or, better still, maybe somebody came along wanting to build something expensive and wrote them a big, fat check!