The answer to Liberalism dying isn't more Liberalism. Liberalism is dying precisely because Liberalism is wrong or at minimum, unsustainable. The attitude of the writer is exactly like the fetishists of every dead ideology, in particular Libertarians who argue "Real capitalism hasn't been tried yet!" or Communists who argue "Real communism hasn't been tried yet." These people, Liberals (capital L) included, need to get real and understand that reality is much more complicated than their specific simplistic idea of Utopia.

To save Liberalism, rather, we must first accept Liberalism is wrong. Then we must discuss what was wrong about it. Then fix those things to invent whatever ruling ideology comes next.

Here's a hint and it comes from his own writing. The "critical theory" and "identity politics" coming from within are directly a result of the nihilism and pathological individualism, respectively, that is born out of Liberalism. The US is degenerating because it lacks a prescribed morality (an unequivocal definition of what is right and wrong) and a prescribed universal identity, respectively. Things that Liberalism eschews, and things that people will find or invent elsewhere despite how many times you bemoan the death of enlightenment ideals.