When the GOP ceases to exist.
And I think if the GOP survived through the FDR years, and the Democrats survived the '80s, they'll both certainly make it through most anything. We haven't had a permanent new party since 1854, LOL...
Essentially this. Hell, the 80s weren't even that bad for the Democrats. I mean, they survived being blamed for the freaking Civil War.
2003 to 2007 were arguably worse than 1981 to 1987 for Democrats. I could see Libertarians becoming a much larger share of the Republican Party if they don't quite win the senate or if they didn't win the house in 2010. The fact that they lost 2 and a half elections in a row probably has made it that they focus on old school 1920s Republicans than fundies or neocons. I'd imagine if they do well this year, they will probably run pretty similar to the way they did in 2000 and 2004 in 2016 and keep running like that until they lose again.
What's more interesting is the prospect of a Liberty movement in the Democratic Party. This election probably means that they can't really count on going back to Southern Dems (They are poised to lose all or all but 1 statewide race in the South). If they lose states like Iowa and Colorado, it probably means that gun control people can't deliver, either. There are groups that DO deliver for Democrats and a lot of their concerns can fit into a Liberty-style framework. Democrats going forward can turnout out more minorities and young people. In a liberty framework, Democrats can be more comfortable on social issues, try to work to make Dovish/ pro-Civil Liberty policies more implementable and effective and try to assail policies that merge state and capital in a way that hurts the little guy. They will have to start talking about "keeping the politics of the moment out of gun control" . However, just like the Republicans, there will be some issues that Democrats won't be able to be totally libertarian on. Healthcare and taxes on the very, very wealthy will have to be how Republican liberty people have handled personhood.
The only thing that would make Democrats to be more successful with a traditional liberal platform is if labor somehow rapidly makes a comeback.