Picking from the list, I picked rebreathers. Over the next 10-20 years.
Industry-wise, I would say fewer independant dive shops, the expansion of online sales, maybe the appearance of some more discount-type volumne based chain shops, and more independant instruction (my last course was through an independant instructor). Shops that can't survive on meagre gear sales that discount training will fold. The availability of "dark grey market" rebuild kits will result in manufacturers bowing to market demands and providing service courses and parts to any diver rather than just dive store employees, further adding to the demise of independant stores, and perhaps helping build an industry of scuba service centers capable of servicing any brand of gear (like taking your car to Sears).
Gear-wise, I would say more and more adoption of hogarthian-derived rigs, be it an increase in donate-from-the-mouth hose configurations, or an increase in the prevalence of back inflate / backplate and wings rigs.
Diver-and-certification-wise, an increase of intro-to-tech type certifications as PADI charge ahead with TecRec or whatever they call it type courses, and a greater acceptance of DIR as recreational instructors start teaching this style of diving, and eventually a PADI DIR specialty :tease:
okay kidding on the last one