With regard to the Mac I am not sure what you are envisioning. But, No. Mac OS 9 Will never be "underneath " OS X in the manner that DOS "was under Windows. OS X is a Unix based operating System. OS 9 is a completely different OS with no relationship to OS X.
I am not sure about the current versions of Windows, but Windows used to be a shell written over the DOS code. The relationship between Classic and OS X is almost the reverse of this.
Steve