20-Year Prospect
The job of bookie will change and grow as state laws are rewritten and technology improves. Gambling is becoming more and more popular, leading states (many of which are already licking their lips at that precious state gambling tax revenue) to loosen laws preventing certain or all types of gambling to take place.
Meanwhile, online gambling havens and improved odds-making and streaming technology will provide more opportunities to both maintain a job and build a business without ever having to leave the home. All of this points to a growth in bookmaker jobs of about ten percent or so by 2022 (source). The rules and practices might change, but odds are good they'll still need bookies at the mega casinos.