I keep thinking about Children of Men.
In Tarrying with the Negative, Zizek discusses the temporality of the symbolic. The openness of the symbolic, the presence of empty signifiers, is not simply the rupture of the Real. Rather, it's the rupture of the future, the anticipatory quality of the symbolic (as Lacan discusses in his essay on logical time). Zizek invokes Keynes--capitalism requires avoiding any final accounting; it presumes a perpetual borrowing from the future. Zizek writes:
Lacan's notion of the debt that pertains to the very notion of the symbolic order is strictly homologous to this capitalist debt: sense as such is never 'proper'; it is always advanced, 'borrowed from the future'; it lives on the account of the virtual future sense. The Stalinist Communist who gets caught in a vicious circle by justifying his present acts, including the sacrifice of millions of lives, with reference to a future Communist paradise brought about by these acts, i.e., who cites beneficent future consequences as what will retroactively redeem present atrocities, simply renders visible the underlying temporal structure as such.
To imagine the world of Children of Men is to imagine an end to capitalism--no borrowing against the future. But it is also to imagine an end of meaning, the impossibility of sense insofar as the horizon that structures a world, that makes meaning possible, is missing.
How impossible this is becomes clear, I think, in the PD James' book insofar as the Warden of England (the dictator) nonetheless justifies his authority with reference to a future--to a near future that is already arriving. He promises security--and people experience his efforts to deliver it. In fact, he relies on the shared insight into the impossibility of a future that is rapidly approaching in order to justify brutal, racist policies. Precisely because there is no future to judge him and everybody knows that they accept his policies. They aren't accountable to a future.
I wonder, then, if we encounter a limit or problem with Zizek's emphasis on choosing the worst, on accepting that the big Other doesn't exist, in his relentless critique of the false security offered by ideology: the alternative of no future, of simply now, is not without its own promises and deceptions, its own sacrifices. Sacrificing others, everyone else, is much, much easier when there is no judgment, no determination, nothing that follows. One has no need for a retroactive justification--or even for responsibility for the world that one's acts bring into being.