What if?

I mentioned that I'm reading Stephen King's new book, 11/22/63.  The plot revolves around the main character who discovers a time portal that transports him back in time to a September day in 1958.  He takes it upon himself to prevent some local catastrophes and discovers how difficult it is to change history.  As King writes throughout the book, "History is obdurate."

I have not yet finished the book, but that hasn't stopped me from wondering how the world would be different today had Oswald missed the president that fateful November day in 1963.  Oswald's wife, Marina, testified to the Warren Commission that Oswald was the person who attempted to assassinate the bigot, segregationist, jingoistic, John Bircher General Edwin Walker in Dallas in April, 1963.  He missed - and from a range much closer than his shot at the president a few months later.  What if?

What if Oswald had succeeded in killing Walker?  Surely he could not then have shot at President Kennedy 7 months later in Dallas, right?  What if he had missed both times?  How would the world be different today?

Would Kennedy have escalated the war in Vietnam as Johnson did?  How many lives hung in the balance of those shots that Oswald took?  Surely, RFK would not have been running for election in 1968, right?  How would the world be different if he had lived?  And how did Kennedy's death affect the arc of MLK's life and death?  And the impact on our country?