It's said in the book that one of the many things Michael learned from his father was to have your enemies overestimate your faults, and your friends and family underestimate your virtues. Michael pulled it off in spades, and everything came full circle during the baptism scene. By Part II, Michael was presumably the most ruthless mob boss in the history of the American Mafia, wiping out nearly all of his enemies. The scene in the boathouse, where Tom tells Mike it's impossible to kill Roth, it reminds me of the scene in Vito's study, where Sonny and the caporegimes are making the "hit-list." Tom says something to the effect of "The key is Sollozo, you take him out, everything falls into line." Sonny wanted to hear nothing of it. In the boathouse scene, Tom asks Michael "You've won, do you have to take everybody out?" Mike says "I don't feel I have to take everybody out, just my enemies." To sum it up, I don't think Mike even sought the respect of the rival Dons, seeing as he took them all out. He didn't seek respect from any of his enemies, he let his actions speak louder than words.