Certainly it could be depending upon its acceptance worldwide firstly and secondly if country allows the gambling as legal for that matter. So bitcoin could be future of online gambling but still need wait for a long time to see many gambling site will accept bitcoin as a one of a payment.
Bitcoin has already taken over the gambling industry and if you look at all the gambling sites major sites will accept bitcoin soon and there are new business ventures started because bitcoin existed and so bitcoin is currently leading the gambling industry as you can see big whales in bitcoin based gambling sites wagging hundreds of bitcoins per day.