PDC chairman Barry Hearn has revealed a timeframe on Luke Littler becoming a millionaire in the sport – and it is not long. The 17-year-old has had an incredible year in darts after reaching the World Championship final in January, which he lost to Luke Humphries. But Littler has already been hugely successful, winning several tournaments – including his maiden year in the Premier League up against former world champions like Michael van Gerwen, Michael Smith and Gerwyn Price. And his success has seen his bank balance bulge and he has already bagged over £364,000 in prize money alone. And PDC …