These niche displays are offering less and less benefit compared to more mass-produced display technologies as time goes on.
All of the upsides of transreflexive displays that are downsides for other displays can be overcome with a $10 battery pack, or by doing things like making the processing and LED backlighting/OLED displays more power efficient.
How is transflexive LCD going to compete with emerging technologies like tandem OLED in terms of overall picture quality, brightness, and certainly having reasonable enough power efficiency? If you can surf the web for 10 hours without plugging in your iPad Pro what aspect of a transflexive LCD device is going to convince you to give up the best looking display on the market?