It would probably incredibly brutal and many would die early on, but as long as enough people survived the initial transition and found some sort of stability,

It would probably incredibly brutal and many would die early on, but as long as enough people survived the initial transition and found some sort of stability, humanity would carry on. Even if conditions were generally terrible, just a few areas where the survivors can grab a toehold could be enough. The prospect of a grim, untimely death for yourself and everyone you love would be rather motivating.