When the full house at an upscale Mumbai multiplex gets up, applauds and whistles during a climactic action sequence in a Hindi-dubbed Telugu blockbuster, you know something is fundamentally changing. The S.S. Rajamouli directorial, RRR, the movie in question here, is one among a series of films from south India that have taken the box office by storm, changing the basic tenets of success in Indian moviemaking. The Hindi film industry, with its marquee production houses, megastars and marketing prowess, is proving to be a feeble competitor to the southern juggernaut. Sample this: a CII South Media & Entertainment report says 62 per cent of the all-India box office collections of movies in 2021 came from south Indian films. And this trend is getting stronger. According to estimates, KGF: Chapter…