Most likely the GOP is entering a wilderness phase, similar to the Democrats in the 70's and 80's.
Democrats had huge majorties in Congress and state legislatures in the 70's and 80's. That's hardless "wilderness".
And I don't see the Republicans being shut out of Congress for the next decade or two. But, with the exception of Our Friend Jimmy, the Democrats failed to control the White house since Johnson in 69 all the way to Clinton in 1993.
Who cares about the White House? Its Congress that makes the laws and sets the agenda.
History does, usually.
It seems that Republicans have had a good line of succession in the Republican Primary.
1952 gave us Eisenhower, Nixon was his VP
Nixon was the nominee in 1968
Nixon served from 1969-1974
Nixon gave us Gerald Ford who had Cheney, Rumsfeld, Bush began big in this decade
Reagan served from 1981-1989, George Bush was VP
George H.W. Bush gave us George W. Bush
Where do we go from here?
George W. Bush beat John McCain in the 2000 primary,
John McCain beat Mitt Romney in the 2008 primary...