I honestly think that who controls senate seats, governorships, and state legislatures are outside of the parties control and just seem to ebb and flow depending on who's prez and other things. The GOP got lucky with Obama because their hatred of him was a great motivator for their electorate. But now both the Clintons and the Obamas are gone and their's no one left to motivate the hate of the GOP electorate and the GOP's policies are going to hurt their own electorate more than anyone else.
I would also add that at any one point there are structural reasons why one particular party can't win much in a certain region. Pretty much no matter what Republicans do right now, they aren't winning a legislative chamber in California nor are Democrats in Georgia. And if you go back in history, a big part of the Democrats' perpetually inflated numbers in Congress and in the states came from its generations-long domination of the South.
As bad as things seem today for Democrats, they are still nowhere near as bad as things were for the GOP when Reagan was president
Those numbers I do frequently like to point out to people who obsess over the number of seats lost in the Obama era, as if this sort of loss of power is unique to any political party. Republicans spent much of the post-WW2 era up to the 90s as a distinct minority party at almost every level, and during Reagan and Bush1's time - this was arguably one of, if not thee worst stretch of GOP power in state legislatures in the post-WW2 era.
In fact, if you notice, in terms of Governorships, 1970 - 1992 was the worst post-WW2 period for GOP gubernatorial success. They never cracked 25 and had less than 20 most of that time. This directly coincided with their 20 out of 24 year run in the White House. The fact is, who is president at the time greatly affects party power downballot, regardless if they are some figure like Reagan or not. There is no free ride in the White House.
As for the Reagan Revolution - I'd argue that was more of a symbolic and ideological turning point for the GOP. I think that the GOP was likely going to take back Congress eventually regardless if the GOP had Reagan during the 1980s or just some moderately likeable placeholder. However, I do think Reagan's influence over young people at the time - younger boomers and genx'ers, helped prolong the GOP's political dominance. The GOP relies a lot on the people that grew up during the Ford/Carter/Reagan/Bush years, so I guess actually even that respect Reagan didn't help too much more than the others.
Reagan actually left with more house and senate seats when he left office then before he took office unlike most post War presidents
House seats before Reagan(1978-1980): 158
Senate seats before Reagan(1978-1980): 41
House seats after Reagan(1988-1990): 175
Seante seats after Reagan(1988-1990):45
