There's no AHL team waiting for Manchester in the wings. The days of the high density AHL Northeast strongholds with Worcester, Lowell, Springfield, Manchester, Portland, Hartford, and Albany all having strong AHL franchises within a stone's throw of each other are done. Markets evolve or die. Atlantic Canada preceded New England as an AHL power region, with St. John's, Saint John, PEI, Cape Breton, Fredericton, Halifax, and Moncton all having teams. They all either joined the Q or died, save for St. John's who floated between teams and leagues and have finally settled on the EC.
If Manchester doesn't survive, then you'll see a trickle down effect. There's plenty of hockey options around them. Boston is more of a commute than a hike nowadays. Take Lowell for example. UMass-Lowell bought the arena and the AHL Devils left after a bit of a messy lease negotiation. Those former minor pro fans became college hockey fans. UML, even during their down years, is still a hot ticket and average attendance is rarely below 5,000. The same thing will probably happen in Manchester, fans will find somewhere else. It isn't going to be a new team that pops up, but people will gravitate to other established hockey institutions.