David Hyslop has been in the orchestra management business for 40 years. He has worked for orchestras from Elmira, New York, to Portland, Oregon, and has been the top man at two major American orchestras. This weekend, he steps down after 12 years at the helm of the Minnesota Orchestra, confident that the orchestra industry will weather the ongoing economic storm, but admitting to a few questions about the sustainability of the current economic model. “The key thing — and the challenge — is that the 52-week season, whether it’s here or in any other market our size, wasn’t driven by market demand but by labor.”