Just to address this part of your post, NiCd cells are much more durable than NiMh or Li-Ion cells. They can hold up to much more abuse, such as over discharging, reverse charging (which can occur when cells are used in series applications), and generally, are simply much more tolerant of harsh conditions whether introduced by the user, or the environment.
Also typically, a quality (think Sanyo Cadnica) NiCd cell can last 1000-2000 cycles vs. the 300-500 cycles that can be expected from NiMh or Li-Ion cells. This helps offset the disadvantage of their lower capacity, to some degree anyway.
So all in all, NiCd cells add a bit more security/stability when used in demanding situations, such as LEO, emergency, and maintenance type of work, than the other chemistry options. For this reason, I think they'll be around a bit longer in this type of use. The biggest drawback to NiCd chemistry cells is their impact on the environment, and for the most part is why they are being phased out. This could be checked by implementing stricter more efficient recycling programs, but......
Dave