Not quite, though the final burst of the demon bubble would likely have left one final regression on Sango before it's effects went away, so she would end up VERY pregnant with a third of Kagome's essence (basically, she's now expecting a baby Kagome :3) and rather regressed. So massive belly on cute and small young Sango at the most, maybe even some of Kagome's physical traits added or mixed with her own for good measure.
Something of note, the entire story for this isn't just preg based. In fact this is the only preg related ending right now. The other possible endings have different effects occur as well. After all, this is only two emotions: Attraction (preg expansion) and Embarrassment (Age regression).
