There's already been lots of discussion about the Trump/Goldwater analogy and a fair amount, more recently, about the Trump/Nixon analogy. Both of these provide some interesting points to explore, but what strikes me is most important here is where the analogies fail. At the risk of oversimplifying, the extremism of Barry Goldwater and the corruption and abuse of power of the Nixon administration both qualified as comparable threats to the Republican Party. The GOP was able to weather these threats with no lasting damage in large part because it successfully distanced itself from both men.
Along these lines, check out the following from Carl Bernstein of Woodward and Bernstein fame:
Bernstein called back to President Nixon's Watergate scandal, and said the "heroes" of the scandal were the Republicans in Congress. "The heroes of Watergate were really Republicans, they were Republicans in the House and the Senate who wanted this investigated to the bottom: What did the president know and when did he know it," he said. "That's what we're not seeing here. We're not seeing it from the Republicans on the Hill who are consumed by supposedly looking for leaks."
We can go back and forth as to whether or not Bernstein is overstating the heroism here, but what matters for this discussion is perception, and clearly the GOP was able to create a perceived distance between its legislators and the Nixon White House. If Russia does end up playing a significant role in the end of the Trump administration, it is fairly safe to assume that future Bernsteins will not describe Devin Nunes as a hero of the process.