Monday’s announcement of a .5 billion merger between Zillow and Trulia might mark the advent of the next wave in how people buy and sell homes in the U.S., experts say. Seattle-based Zillow, the market leader in online residential real estate listings, said it would buy the second-biggest player in that market, San Francisco-based Trulia, in an all-stock deal. Following the announcement, Wharton real estate professor Susan M. Wachter discussed the pairing on the Knowledge at Wharton show on Wharton Business Radio on SiriusXM channel 111 . Wachter talked about what lies ahead for Zillow-Trulia and the housing industry. (Listen to the podcast at the top of this page.) The combined Zillow-Trulia will achieve cost savings and invest more in building its online platform and resources, according to the announcement.…