depends.
theres male pattern baldness and theres Telogen Effluvium (shock fallout)
if you arent predisposed to MPB, and you are one of those who get a shock fallout, it will grow back to what it was.
if you are predisposed to MPB,
1) even without a TE, a cycle will accelerate the loss and there wont be growback
2) if you also get a TE, the hair outside the traditional MPB area will grow back, and the hair within may or may not, plus whatever acceleration factor because of the cycle