I think Reagan was more than just a flash in the pan. His commitment to reducing marginal tax rates from 70% to 30% or so and to supply side economics (people responding to incentives) has had long lasting effects not just in the US but elsewhere.
Except for that observation, post #14 is spot on.
I imagine the Reagan as “flash-in-the-pan” stems from his two poor Supreme Court nominations, one of which was practically an outright shill for liberals.