In terms of recreational diving, I don't think we can go much further. I learned to dive in 2009 so I haven't experienced some of the kit those that have been diving longer have. Like many, I learned with the typical recreational set-up with a jacket style BCD. When I started to dip my toe in technical diving, my kit got a lot more basic. Okay, there is more equipment but the kit I use has no unneccesary thrills. I do not think the typical recreational kit needs to evolve much mure, however, manufacturers will all want to produce the latest must-have gadget. There have been some nice little touches, such as OLED technology as mentioned but nothing that I think has changed the way we dive.
I do like some emergency kit, such as the EPIRB and diver carried VHF radios. Underwater GPS would be nice and these buddy/shot line locators look interesting, but I don't think I'd bother.
Liquid breathing / artificial gills would be interesting but probably not going to be a reality anytime soon.
The future is going to be in affordable and RELIABLE CCR. When they can be bought and maintained by the average diver, dropping it off for its annual servicing and be as safe and fool proof as open circuit, that will be huge.
I find the concept of simple CCRs equally interesting and disturbing. I am a recently qualified IANTD Mod 1 CCR diver and the prod owner of an AP Evolution+. The rebreater is complex, but at the sime time logical in operation. On the Mod 1 course, I was taught about the voting logic of the controllers, how the cells provide information to the controllers and how to interpret the raw data. My instructor often refered to being the 'thinking diver' and reminded us on several occasions the rebreather does not have a brain.
A lot would have to go wrong with the rebreather before I could not use it - I can deal with problems such as a solenoid stuck open or failing to operate, and only a few faults would need me to completely bail out. I would much prefer to know how to identify and handle problems than trust something because it's considered reliable.