You make excellent points, LW. But, at that point in Michael's life, I doubt he was thinking along those lines. The fulminel was still ringing in his ears. And, he was probably figuring that Sonny would be the head of the family until Vito recovered, and he could return to "civilian" life. Of course Apollonia would have been a hindrance to to his obsessive quest for "legitimacy in his Donship, as you said. Hence his bloodless, passionless wooing of Kay in New Hampshire after his return.

This leads to another question: Do you think that he told Kay that he had married in Sicily, and that his bride was killed by mistake by a bomb intended for him? Would Kay have agreed to marry him if he had?