No it most likely will not come back. Its not the groomers fault, it would have eventually grown out to the new color anyway. Their colors can change soooo much. Its just you usually dont notice till its cut off. Cutting hair doesnt change its color. Many people dont notice how light the roots are, and then when they get their hair cut off short thats all thats left, so they look like a new dog. So many people think because the end of their hair is dark thats what it should still be. I have had so many people think it was cause the groomer cut it off that it changed, but that is not the case.