Wait, when did Infernals become an inevitability, again? The Yozis are *built* out of souls... if Infernal Exalted have to exist, then they're probably temptations- the Yozi has incorporated the Essence into itself, and uses the Exaltation as a method of permanently binding another soul into its structure. More likely, though, the Essences have been incorporated *within* the existing Yozi structure... Weapons with which to break the world.
If you've ever seen the Final Fantasy Crystal Chronicles commercial Nintendo did- that's one of those chords that really resonates for me. If you haven't, the basic scenario of the game is that the world is blanketed in a foul, toxic miasma that destroys or warps animal life and only crystals that have been purified with a certain sort of nectar can hold it off. The commercial shows an empty, modern city with a noxious-looking fog rolling through it; the camera flies up to the roof of a skyscraper, where four rather ordinary (if determined)-looking people stand at each corner. One grins and raises a glowing crystal...
In Exalted Modern, I imagine the Sidereals held practically impotent- mending fates and averting disaster, clinging tooth and nail to a very long-term plan but constantly struggling to keep abreast of the changing world, and the Malfeans buried deep and fitful in the earth. The Yozis have incorporated themselves more into humanity than demon-life, and rather than deep and consuming evil, most of their incarnations are medicore; likewise barely holding on. The Celestial Beauracracy is more or less gone, the scattered gods struggling to eke out an existance in a world that has forgotten them; the strongest remaining organizations are deeply entrenched in governments and organizations such as the Mafia. The Lunars are nearly wiped out, their Essences incarnating only in the deepest jungles (urban or floral). The Terrestrial bloodlines are dilluted among the nations of the earth; the Sidereals keep tabs on their genetic legacies, killing or recruiting any who are likely to Exalt. The Solars defeated the Deathlords, who were broken and scattered or sent screaming into Oblivion- then, their Essences exhausted, the Solars fell into an seemingly endless dream.
Most of the Deathlords, anyway. When the fourteenth one awakens, he brings the end of the world with him.
Unprepared and unprotected, the mortals of the city where he rises die in droves. The new 'plague' wipes out most of the East Coast; the area bound by New York, Philadelphia and Boston quickly becomes a massive shadowland. The Sidereals, spread across the globe, begin to respond- but not nearly fast enough. The Lunars in these cities fight back, but are beset by literal armies of undead. The smart ones go to ground; the others die.
The Unconquered Sun, driven distant by the changing world, seems to grow brighter in the sky; the sleeping Solars rise in the cradle of civilzation, the edges of Europe and Asia, but primarily the ancient Middle East and northern Africa- even as the heat of the sun blazes and the tides rise. The city of angels, the strongest American residence of the Beauracracy, miraculously remains above the rising waters; much of both coasts are swamped, and earthquakes and tides devestate the cities as Gaia and Luna begin to rouse. Still, the powers of the new Deathlord are great, and his cities stand; towers of bone and sinew rise to brace the skyscrapers- eerily still lit- and opportunistic nemessaries appear as Ambassadors of the Principality of Drowned Skies, expanding the sway of their master's domain (It is wonderful, these ways we have of killing now; often the body is hardly marked, and with the right chemicals, a governor or mayor who meets some accident, or perhaps succumbs to a weak heart or tense mind, might continue to govern (with some assitance from those who are skilled in such matters) for weeks, months, or even years beyond his untimely demise). The surviving remnants of the older Deathlords stir, and the newly awakened Solars must face them before they can depart for the darkened America. Lunars and Sidereals engage in a guerilla war with the new Deathlord, recruiting mortals and reluctant forgotten gods.
And the shards of the Yozis begin to remember dreams of the glorious dark empire they would have built... Many, more human than demon now, struggle with themselves... the Malfeans turn fitfully, and rumors of strange 'aliens' increase as the chaos rises...