To be really honest with you, I don't know enough about the history of 20th C architecture to have an opinion. The most I feel comfortable saying is that the major figures seem to have been influenced by Cubism.
The bright Greco/Roman Era transformed itself into the dark Byzantine Empire. We might be in the same historical parallel at his time in the picture. If that is the case, there are a few 20th century examples that might show us what's to come.
Right now, it does seem likely that history will call these times a watershed moment. The turn of the century, the turn towards a more realistic view of life. Perhaps architecture will reflect this awareness with structures that reflect a new soberness and connection with our own sense of mortality - something we seem to have forgotten in the last decades of the last century. IMO, as always.
A few years ago I was in Mohegan Sun Casino, in Connecticut. After I lost all my money and I borrowed a few bucks from my friend to buy a drink, while I waited for him to lose his money. Anyway, I got talking to a guy at the bar who told me the whole underground complex was a former assembly plant for nuclear warheads. ( Short distance from General Dynamics Electric Boat) But, since the military downsize of the post Cold War era, the Mohegan Indians managed to buy the plant and turn into a casino in the 90's. Sure makes one wonder how many leftover obsolete secret underground plants and silos exist in America? I watched all through the 80' everyone transform former 19th century manufacturing plants into office space, and this future transformation, of these secret spaces, does not appear far fetched. What other type of architecture would be more secure and insure record safety for commerce?
The last casino I was in was a gigantic pyramid. More stable, may have withstood the blast better. But to address your question, seems to me there are multiple factors that could improve safety. Spatial configuration is one, choice of building materials is one, height above the earth, protection surrounding the structure come to mind. This is assuming a traditional approach to structure. Perhaps we need to reconsider our idea of structure. To borrow a thought from the enemy, perhaps decentralized structures connected by contemporary communication equipment would protect us better. Instead of concentrating people and resources in one location, scattered locations with less obvious, harder to locate and hit, easier to evacuate buildings. Buildings could be located out in the mountains - build a building that looks like a mountain! or the desert. They could be designed to appear to be part of the surrounding terrain, whatever it is. A building that is an island. A building that is a mountain, or that has a forest growing on the roof. Or underground, utilizing existing excavations, recycling human labor. Guerilla architecture? Integrated architecture?
The new monumentality, as you said, might not be phallic or outward. There's also one more example of 20th century architecture that fits into this. It's that Haute? something by Corbu, the chapel that looks like an upside-down boat. It has very Byzantine feel about it. Thick walls, dark, small windows, and candle lit. Before this thread that chapel made no sense to me.
Monumentality has to do with scale, not directionality or configuration, imo. I suppose it could be argued that a revolutionary idea is ENORMOUS, and therefore would register on the scale meter, but usually we are talking about scale as measured by a human form. The Haute? is the Notre Dame du Haute ( is it du or de?) The building you cite is a prime example of what we seek in this conversation; it was designed immediately *after* WWII, when Corbu turned away from the purity ( sorry) of his early work and turned to rougher, more expressionistic design and material. WWII marked a turing point in his outlook, obviously. More inward, more protected, darker, with light coming in from small high windows. And candles. A spiritual and psychological statement. Interestingly, Picasso's work also travels a similar arc from the cool rationality of analytic cubism to the controlled riot of synthetic. IMO.
The clues of what's to come is right in front of our eyes, only we can't see it. Vaults and arches existed for thousands of years before someone did something with them.
Our children and grandchildren will be able to see them.