Nixon was extremely politically shrewd, perhaps moreso than any Presidential nominee in history. He knew that the
southern stragegy was his most direct and effective path to the White House.
To not pursue the
southern strategy could have thrown the election into the House, resulting in Humphrey winning the Presidency.
However, with the states that Nixon actually did win, and with the scenario you describe, I do not see why Nixon would lose any of the non southern states he actually won in real life. In fact, with your scenario, Nixon may have actually increased his margin in many of the states he did win.
With your scenario, there is a distinct possibility that Nixon would have lost North Carolina, South Carolina, and Tennessee to Wallace, which would have left him with 270 electoral votes, barely enough to win, however, just enough to win the Presidency outright.
Nixon still wins Kentucky, Virginia, and Florida, even with the lack of a
southern strategy. These are states that would not go for Wallace regardless.
Nixon 270
Humphrey 191
Wallace 77
Another possibility in this scenario, Nixon could actually pick up Maryland and Washington.
Nixon 289
Humphrey 172
Wallace 77
