National Health Care is very iffy. Same thing with saving South Vietnam. Both rely on some kind of approval by Congress, and it is by no means certain that could happen. At the same time, it is possible that a President Nixon that stays on and does not have the distraction or liability of Watergate is a sufficient deterrent that North Vietnam doesn't even try to violate the peace accords (or is quickly dissuaded to not do so after some testing) that they choose the option of temporary peace to rebuild the North and try again in ten years or so (which won't happen as by 1985 IOTL the Communist Vietnamese economy was collapsing and required extensive reforms to survive).
TTL Nixon is likely evaluated as a good president - great foreign policy and mixed domestic record. He'll be thanked by many (and hated by a few) for holding the line when it seemed the country was going to implode from left wing radicalism. There is a reason he won 1972 in a landslide. But with no major scandals and OTL's accomplishments, he'd be evaluated positively. Perhaps not in the Top 10, but likely the Top 20 not far from the top 10. And he'd certainly be the foreign policy sage for both parties, Nixon was practically treated as an elder statesman IOTL despite Watergate for the last ten years of his life.
Reagan has a good shot at being the GOP nominee in 1976 without an obvious GOP incumbent. And it is hard to see Carter getting the Dem nomination without Watergate. Scoop Jackson would consolidate the centrist/conservative voters of the Dems while liberals split followed Mo Udall and others. It'll probably be Jackson versus Udall for the nomination with Jackson the likelier nominee, but not definitely so. In either case, the country is taking a rightward turn.