In the civil war between Donald Trump and the GOP’s waning establishment, no Republican has crossed the former president and come out ahead. Yet as Rep. Liz Cheney’s likely ouster from House leadership lays bare, Trump has reserved a special fury for the scions of the GOP’s leading families in his attempt to exercise full dominion over the Republican Party. Whether it’s the Cheneys, the Bushes or the lesser bloodlines — such as the Romneys or the Murkowskis — Trump has been relentless in his efforts to force them to bend the knee. Even Cindy McCain, the widow of the...