MTV hopes to begin a new era in daily talk and social media on Monday with “It’s On With Alexa Chung,” the eagerly-awaited replacement for “TRL.” The network describes the noon show, hosted by the half-British, half-Chinese ex-model and TV personality, as “a live, daily talk/variety show featuring interviews with the hottest celebrity guests and musical performances from mainstream and indie artists, along with Internet-found talent and topical pop culture news.” Jack Black and Michael Cera, along with musician Soulja Boy, are Monday’s guests.