They'll kill off whatever percentage of the working class they don't need like they did in WW2 during the last great depression, although I'd argue they have more efficient methods of purging the working class now. They'll make everyone so poor they beg to fight in a war, like in the 20s-30s.
Russia is already doing this, USA is gearing up for a war with Iran but can't see the USA wanting the PR of losing many soldiers, they could just increase the forces so basically every working class person is low paid potential cannon fodder.
The difference is that in Russia those who are willing to go to war have lived in poverty for decades already, those are not middle-class Muscovites who prefer to stay away from it (in terms of direct participation).
But another thing when a lot of middle-class citizens are plunged into poverty in the short term - that will look more dramatic and unpredictable.
