I don't believe there is any requirement in the *A for at least one member airline to operate at least one *G lounge in every airport they fly to/from. They could simply convert all UCs to Polaris lounges and you would have no recourse. Or they could turn the only UC lounge into a simple room with small snacks and drinks and no restrooms, similar to HA's "lounge" (if you want to even call it that) at OGG.