Continuing the discussion from Geneve 9640 - the "other" TMS9900 based micro:
Nice links! There’s a comprehensive site all about the ns32k which includes a page on CompuPro’s offering:
http://cpu-ns32k.net/CompuPro.html
It does at least seem that S100 can offer 16 bit wide memory.
The ns32k was a very CISCy CISC, which took very many iterations to get right, a lesson which Acorn took on when designing the ARM.
There were, and are, quite a few 16 bit systems on S-100. It is still alive (and well!) today, with new boards being designed, including PDP-11s, 486s, and more. Take a look here.
Edit: It’s just hard to find the connectors 
The original Altair had 8 data in pins and 8 data out pins. For the S100 / IEEE-696 standard they allowed the processor and peripheral board to agree to use these 16 pins as a bidirectional 16 bit data bus instead. In addition, some spare pins were redefined to extend the address bus to 24 bits.
See a comparison of the pinouts for various S100 machines.