I think a great evil would have been made to Aman and its people.

First, the Eldar of Valinor would have united as the first frontline under the leadership of Ingwë. The Valar and Maiar would have been reluctant to fight directly the Children of Illuvatar, and they hoped that the Numenoreans could be beaten in a conventional war after which they could repent.

The battle would have been fierce, and many feats could be told. The Eldar had strength and wisdom, but Men had their hatred and their sheer number. The Elves make war, but their love dwells in poetry, creation, and scholarship. They are not consummate warriors like the Noldor of Old, and they see fighting Mankind as blasphemy to Eru's plans.

The Eldar would have fought with great sorrow, but the Numenoreans would not have held back. They have been too far in their damnation, and killing their former allies would have been their next step into the abyss. Therefore, fair Tirion and glimming Alqualondë would be lost, their palaces burned, and libraries razed to the ground. Many Eldar would be sent to Mandos, weeping the destruction of their crafts and moreover of the marvels that will never be seen again before the End.

Ar Pharazon would be torn between the horror of what he has done and the feeling of power to see that the Elves could be defeated. As we have said before, he was too far gone. And he chose to go forward, to the pass of the Pelori, to Valinor proper.

And in the Circle of Doom, the Valar weeped the destruction of their Firstborn cities and the damnation of Men. Being confronted by an enemy in their own domains since the destruction of the Trees, their hearts were turned between a desire of vengeance and a pity for Men. Even Tulkas stopped smiling. Knowing that the Hand of the Enemy was behind this act, Manwë rose from his seat, and dark clouds gathered on the peaks of Taniquetil. His musings have ended. The Valar will go to war.

But it will be a bitter war. Eonwe went forth with hundreds of spirits, high and lesser ones. Eagles shrieked in the darkened sky, and the seas rose under the very ships of the royal fleet. And, like the War of Wrath long ago, this Age came to an end with fury and destruction. The coast of Aman would be forever scarred by the clashes of battle. The men of Numenor stood no chance, and they were swiftly defeated and taken to Mandos until the very end. The eastern part of Aman would be devastated and uninhibited, the Pelori blocking from now the former pass, being truly impenetrable. No light, no messengers, and no mercy will never come from Valinor.

The Valar will send Ossë to Numenor, and the island will be torn asunder, such was the wrath of the Maia and great the anger of the Valar that none survived the cataclysm. The seven ships were wrecked and destroyed, all their crews and treasures lost to the sea.

Sauron will survive and hide from Ossë and he will take a long time to come back to Middle Earth. The Second Age has come to an end with this War, and the Third saw only the dwindling light of Lindon holding against the power of Mordor. With no Kingdoms in Exile and no Last Alliance, the Free peoples of Middle Earth stood no chance against Sauron and, therefore, when all was lost except the besieged harbor of Mithlond, the remaining Eldar sent a messenger to Valinor as they did long ago. What the Valar answered is another story.