Don't know about you but my ( lead acid ) car batteries last a few years, won't know for a while what the longevity of a NEAH battery may be. As for temperature resiliency another unknown. These may be measured out and predicted by DOE research but nothing to count as an advantage right now.
NICADs are batteries of choice for telecoms with equipment in high heat cabinets plus for longevity ie. more than 15 years, more like 15 to 30 years supposedly...is this gonna compete with that ?
I haven't seen any Lithium batteries that aren't degraded after a few years.