This is conversation is getting close to what I believe Anbesol mentioned in his start of this discussion.

ISO alone is meaningless as it is an arbitrary legacy measurement that could be argued that we don't even need any longer.

Where shutter speed and aperture (just to mention two) are settings/parameters for exposure that have a physical measurement that goes with them that is universal . . . ISO numbers are based on a 'standard' that never was very standard in its implementation. Ergo why we shot film pushed/pulled or always shot at something other than rated for some emulsions.

None of this would be possible without dramatic improvements in dynamic range capability and not just end-to-end increase but the increase in uniformity of linear response of the sensors in all their critical measurements.

Framing rate of a sensor also plays a critical role in the modern DSLR and that isn't how many frames per second you can shoot! It is how long it takes the sensor, not the camera, to be recycled/discharged/charged and internal sensor buffer cleared to be ready for the next shot. That's important in determining how long it takes for the heat to dissipate that creates added noise. Or you can just use a lot of in-camera processing to speed up an older fab of chip. This as much as any combo of factors gives us the current ability to amplify the signal, i.e. turn up the ISO equivalent rating.

NOTE: Canon has announced that they have obviously pushed the framing rate a bit to far with the 7D as previous images can appear to overlap one another in continuous shooting mode!

Do we need ISO much longer?? Or should we start pushing for a setting that is low to high(acceptable) noise? We have Auto-ISO in some implementations now. Marketers want us to compare how large our numbers (ISO) are as it keeps selling new stuff!

Personally I like having the added option of lower noise at higher 'sensitivity' to simplify or ease further control what I do with light. It isn't though a magic bullet to great photos.