What if Ted Kennedy hadn't gotten Mary Jo Kopechne killed at Chappaquiddick in 1969?

Times have certainly changed since 1969, and, if Ted Kennedy had done today what he did to Mary Jo Kopechne in 1969, he would certainly have gone to prison, quite possibly for murder, and quite possibly for life. However, as it was, her death resulted in scarcely a pause in his career. He remained a powerful and influential Senator for decades, and, in 1980, he almost took the Democratic presidential nomination from incumbent Democratic President Jimmy Carter. What if Ted Kennedy hadn't killed anyone? I suspect, absent Chappaquiddick, Ted Kennedy would, almost inevitably have been the Democratic Presidential candidate on one or more occasions in the 1970's or 1980's. Despite his obvious limitations, he actually was a very, very good politician, probably as good as his older brothers were. Also, let's face it, Teddy had terrific survival skills! Mary Jo may have drowned in 1969, but, not Teddy. How many drunken guys can crash their cars into a river in the middle of the night and swim to safety without getting a scratch? I could be wrong, but, I really don't think if he had been elected President, Teddy would have suffered from the Kennedy curse. No assassination for him, he would have been too careful! So, when exactly would Teddy have run for President, and would he have won? I would say, he had a very, very good chance of winning, but, when, exactly -- 1972, 1976, 1980, 1984, 1988? Would he have knocked off Richard Nixon? Do Jimmy Carter or Ronald Reagan even enter the picture absent Chappaquiddick? What kinds of policies would President Teddy Kennedy have pursued, and what effects would those have had on the American economy, and the international scene? How is the world different today, if we had had Ted Kennedy as President of the United States, and not someone else who actually was President OTL?