Yes, but sub-pixel font rendering is really just a way of fudging things. I remember Microsoft making a big deal about it when they first released MSReader. It doesn't really increase the DPI, it just lets you use part of a dot. Ceteris paribus
, the DPI would be cut to one-third of its original by switching to color, so SPFR would simply get you part of the way back to the B/W version.
I assume, however, that color versions will bring smaller, closer ink bubble thingies and a corresponding increase in pixel density.