Watching Rachel Maddow last night (4/25) I was reminded of
Squeaky Fromme. There you could have a big twist in history. If Fromme had killed Ford, then Reagan would have gotten the 1976 GOP nomination. Carter was a much poorer campaigner in 1976 than he was later and an Reagan would have benifited from a highten demand for law and order. (Two presidential assassinations plus the King, X, and Robert Kennedy slayings would have made the national moood more favorable to Reagan).
Now, given the ecconomy of the period, and the fact that the GOP would have been likely to have done much to get majorities in either body. Reagan would have had a harder time of things. Many of the things Reagan believed in would probably of backfired in the late 1970's which was an ecconomically different period than the early 1980's. Reagan could have been a one term President with a reputation like Ford's.
This would lead to a radically different world by the 1990's. Democrats, and probably liberal ones would be in the White House when the USSR collapsed under its own weight and liberals would get far more of he credit. Renewable energy, space, and other technologies ignored in the 1980's would be more advanced, especially if Ted Kennedy gets elected in 1980. A very different world, with different flautlines.
Perhaps Putin and Bed Ladin might seek allies in the millitia groups of America.