The mayors don't dictate who shops where and when. My guess is that people no longer wanted to pay the high prices for the trinketry and Hallmark cards that Jan's sold. It happens. Businesses lose their uniqueness and fall by the way of the cheaper cards at WalMart.
If they are leaving because of the high rent in the center they are in, that's between them and the landlord and the mayors have nothing to do with those leases.
What you have here is a company that made money here, expanded their business on the back of that success and are now leaving. It happens.