By most accounts, the Bay Area economy is humming along. Yet, to even the casual observer, empty storefronts have a strong presence on Bay Area streets, even in desirable neighborhoods. Among the causes, experts say, is the rise in online shopping and landlords holding out for tenants who will pay higher rents. Another culprit is the cost and hassle of doing business in San Francisco, according to Mayor London Breed. She announced a plan Monday to streamline regulations in the hopes of filling vacant stores. Forum looks at the state of retail in the Bay Area and what can be done to keep our neighborhoods hustling and bustling.