If Ford is indeed Reagan's VP in 1980, and everything goes according to OTL, then in 1984 I think Bob Dole has a great shot at the Republican nomination, if Reagan is dead. Otherwise, is there a chance that 1988 is Dole's year if Ford is kept on until then?
Of course, Bush's political career takes a hit. It will be harder for his sons George W. and Jeb Bush to get elected in this TL without their name recognition.
Let's see:
1984: If Reagan lives past the assassination attempt, then it would be:
Reagan defeats Mondale
1988: Dole defeats Dukakis
1992: Clinton vs. Dole? Maybe. I'm not sure if Clinton wins; maybe some butterflies will help the economy, or at least Dole's chances for re-election. Also, butterflies may hurt Clinton's nomination.