If experts are to be believed, San Antonio is finally closing in on its moment. Henry Cisneros, who has written not one but two books about his hometown’s potential, told me so, celebrating the immense changes he has seen since he left the mayor’s office in 1989. “The city is booming,” he said, in the silky pitchman’s tone that he honed during decades as a public servant. “It’s a fundamentally different place.” Fundamentally different, that is, from the San Antonio where I grew up, with its chasmic social, racial, and economic divisions. A city where people would allude to the local “mañana mentality,” a nod to the town’s leisurely pace as well as a euphemism some use to implicitly blame Latinos for its failure to thrive.…