You are listening live from the South Point sports book, which will serve as the hub of Brent Musburger’s new sports betting network in Las Vegas. Banners promoting the iconic broadcaster’s burgeoning Vegas Sports Information Network (VSIN) were already hanging inside the South Point on Wednesday, when it was announced that Musburger will end his play-by-play career with ABC/ESPN at the end of January to help his family start a sports betting venture. Musburger, 77, called countless big events over the past 40 years — welcoming viewers with his signature “You are looking live” catchphrase — since rising to fame…