A little over ten years ago, the same postmortem was being written for the Democrats. These things are cyclical, more often than not, saddled as we are with only two viable/relevant parties at any given time. Moreover: the Democrats certainly haven't recently shown themselves to be very good at "circling the wagons" in mid-term years or in gubernatorial elections, nor of organizing a lot down-ticket support outside of 2008.
I nonetheless do agree with Julio that folks like Boehner and Graham represent a better "path to viability" than uber-obstructionists like Ted Cruz, who'd rather blow up the government than govern. It's an act that gets old, I think, even with voters and legislators whose convictions are similar (but who can hear the word "compromise" without recoiling in abject antipathy). I'd argue that, in no small part, Trump's ascendancy is a suppuration of that fetid boil of frustration—though obviously I think a calming salve would've been a better course of treatment than Mr Drumpf's violent, polemical lance.