Terry,
No, not far fetched from lack of sleep at all.
Most are inplementing 4th axis to the mill. So a takeoff would be what your suggesting.
I have thought differently and that is to add milling to the lathe.
I was fooling around a few years ago on the lathe. Provided a stepper driven spindle, used a high speed rotary tool mounted on the carriage, setup the spindle as linear A and also angular, then with the Z at feed rate and A turning you could machine some nice deisgns over a shaft. I guess i was trying to slave the two axes also. The problem was a stepper for the spindle was not good since you would get changing feedrate which was not linear and limited. (As spindle speed / feedrate was increased the stepper torque was on the down side and the torque required to turn the spindle was increasing). One of these days I'll splurge and get a servo and drive to fool arond with.
The nest step was to add the equivilant of the mill Z axis to the carriage. Still in the works .....just another project to be done.
That thinking was, once a piece was cnc turned, one could do additional machinng / milling without removing it from the lathe. Or do some things that normaly would required the 3D process and avoid setup or transfer of the piece to the mill.
I will remark that the above was for small stuff.
Play with the idea and see where it takes ya,
RICH