Had Martin Luther King Jr. not been assassinated, would he have been President?

[Cashew]

I think he could have won in 1988 or 1992.

I actually think the earlier on the better the odds are for him. The United States may have been more racist in the 1970's, but the new deal coalition was still dominant, however fragile it was. By the late 1980's the country is too right wing economically for someone like him to be electable.

You would need to somehow sabotage a political realignment to make this plausible.(And I doubt he alone is capable of holding back the tide.)