GOP isn't burning to the ground. This bizarro nationalist/nativist thing is on the upswing throughout the Western World. In the US it's the GOP that's been subverted to become the vehicle for it. It won't be ending anytime soon. Trump is just causing a new level of revulsion and activism among Democrats. In the future, there will be GOP players who are less viscerally disgusting, far smarter, and who will be able to push through much the same agenda with more subtlety and without the immediate blowback.
We don't want the GOP establishment to burn. What's left of the party without them? Tea Party wingnuts, white nationalists, and various forms of less virulent ethnocentrist scum? People like Ryan, while repulsive, are the remains of the old school Republican party that's managed to survive from the 20th century and still at least maintain a pretense of core American values. Without them, we're left with burning crosses, isolationists, and walled off borders.