Looks like you are correct. I just need to work it out, longhand.......
I figured the volume difference between the old cell (18mm x 65mm) and the new cell (21mm x 70mm) using this online calculator:
http://www.onlineconversion.com/object_volume_cylinder_tank.htm
18mm x 65mm = volume of 16540
21mm x 70mm = volume of 24245
The volume difference factor is 1.466.
Assuming no better chemistry, but utilizing all the other 100 KW Model S battery techniques, those eight battery modules (with new 2170 cells for a factor of 1.466:1) would notionally become 11.73 "old modules".
11.73 "old modules" divided by 16 "old modules" works out to 73.3%.
So, you are bang on, I worked it out to 73.3 KW capacity (assuming no chemistry improvements).
With the smaller size and better Cd, I wonder what a 73 KW battery pack will give the Model 3, range wise?