Modernity offered, in contrast to the experiential paradigm of the vast majority of human history, a very different vision of man, society, in the universe. As such, it needed a narrative to establish the legitimacy of its vision, which we may summarize thusly:
Primitive man lived in darkness and ignorance, kept their by religious superstition-peddlers. We enlightened thinkers and scientists succeeded in liberating man from his squalor and have set him along the path toward his gradual perfection.
This narrative may have been believable in the 17th and 18th centuries. We, today, know better. Man's liberation from religion has not perfected him. It has loosed horrors beyond counting on the world.
The "crisis of modernity," as such, is the spontaneous recognition of the falseness of this narrative -- and therefore the falseness of everything which has come to be because of it, including our social order, our ethical life, and our self-understanding.
Because modernity is false (and everyone knows it), it cannot be sustained. There are only two options: to return to that which is normative, historical, spontaneous, and organic, that is, to religion, to the traditional family, and various other institutions; or else to soldier on ahead, dropping only those parts of the modern condition that clearly cannot be salvaged.
Western society by and large has chosen the latter course. It has elected to drop, among other things, the idea of a coherent narrative; indeed, it is now characterized by suspicion or distrust of narratives. This, we call "postmodernism." It has also jettisoned its concern for reason, rationality, and the realness of reality. This, too, is part of postmodernism; we call it "deconstructionism." It has retained everything else of modernity, including its parousiasm and dialectic historicism.
But modernism-lite is really no more sustainable than was modernism-regular.