He'd probably manage to be a better candidate than McGovern with a very memorable acceptance speech, but the platform would probably be about the same and so I imagine it's just another Nixon landslide with more racial polarization. The long-term impacts on racial politics and the direction of the Democratic party in such a scenario would be much more interesting than the result in 1972 itself.
Positive consequences for Dems in my opinion. I'm not a huge fan of McGovern's effects, I think King takes the party in a somewhat different direction.