Morgoth was defeated and sent into the Void (space), where he cannot escape and get back to Arda.

Wilt thou learn the lore | that was long secret
of the Five that came | from a far country?
One only returned. | Others never again
under Men's dominion | Middle-earth shall seek
until Dagor Dagorath | and the Doom cometh.

After the triumph of the Gods, Eärendil sailed still in the seas of heaven, but the Sun scorched him and the Moon hunted him in the sky . . . Then the Valar drew his white ship Wingelot over the land of Valinor, and they filled it with radiance and hallowed it, and launched it through the Door of Night. And long Eärendil set sail into the starless vast, Elwing at his side, the Silmaril upon his brow, voyaging the Dark behind the world, a glimmering and fugitive star. And ever and anon he returns and shines behind the courses of the Sun and Moon above the ramparts of the Gods, brighter than all other stars, the mariner of the sky, keeping watch against Morgoth upon the confines of the world. Thus shall he sail until he sees the Last Battle fought upon the plains of Valinor.

Thus spake the prophecy of Mandos, which he declared in Valmar at the judgement of the Gods, and the rumour of it was whispered among all the Elves of the West: when the world is old and the Powers grow weary, then Morgoth shall come back through the Door out of the Timeless Night; and he shall destroy the Sun and the Moon, but Eärendil shall come upon him as a white flame and drive him from the airs. Then shall the last battle be gathered on the fields of Valinor. In that day Tulkas shall strive with Melkor, and on his right shall stand Fionwë and on his left Túrin Turambar, son of Húrin, Conqueror of Fate; and it shall be the black sword of Túrin that deals unto Melkor his death and final end; and so shall the Children of Húrin and all men be avenged.

Thereafter shall the Silmarils be recovered out of sea and earth and air; for Eärendil shall descend and yield up that flame that he hath had in keeping. Then Fëanor shall bear the Three and yield their fire to rekindle the Two Trees, and a great light shall come forth; and the Mountains of Valinor shall be levelled, so that the light goes out over all the world. In that light the Gods will again grow young, and the Elves awake and all their dead arise, and the purpose of Ilúvatar be fulfilled concerning them. But of Men in that day the prophecy speaks not, save of Túrin only, and him it names among the Gods.

The published Silmarillion ends with the recounting of the voyage of Eärendil the Mariner, but this is due to an editorial decision by Christopher Tolkien. The Silmarillion as J. R. R. Tolkien wrote it ends with a prophecy by Mandos about the Final Battle (or the Dagor Dagorath in Sindarin), often reffered to as "The End". The remaining clue to this prophecy is found at the end of Akallabêth, where "Ar-Pharazôn and his mortal warriors who had set foot on Aman were buried by falling hills, imprisoned in the Caves of the Forgotten until the Last Battle and Day of Doom". TThe account is clearly inspired by and bears many similarities to the Norse legend of Ragnarok.

According to the prophesy, Melkor will discover how to break the Door of Night, and will destroy the Sun and the Moon. For the love of these, Eärendil will return from the sky and shall meet Tulkas, Manwë (or Eönwë his herald) and Túrin Turambar on the plains of Valinor. All the Free Peoples of Middle-earth will participate in this final battle, Elves, Men and Dwarves alike. To their number will be added Ar-Pharazôn and the Númenóreans who landed at Aman in 3319 SA.

There they shall fight with Melkor. Tulkas will wrestle with him, but it will be by the hand of Túrin that finally death and destruction will be dealt to Melkor. Túrin will run his black sword Gurthang (Iron of Death) through Melkor's heart, thus avenging the Children of Húrin (Sind: Hîn Húrin), and the Pelori Mountains will be levelled. The Silmarils will be recovered from the Earth, and Fëanor's spirit shall be released from the halls of Mandos to give them to Yavanna, who will break them and rekindle the light of the Two Trees. The battle will end and renew Arda's existence: all the Elves shall awaken and the Powers will be young again.

Following this, there will be a Second Music of the Ainur. This song will sing into being a new world. Men will sing it with the Ainur. It is unknown what the fate of the old races, or of the old world, will be in the new one. Even the Ainur do not know anything of the second world or the Second Music. All the Ainur know is that the Second Music will be greater than the First Music.

The reason for Christopher Tolkien's removal of the prophecy is that the final section of the Silmarillion was written in 1937 and only cursorily revised afterwards. Meanwhile, in the Valaquenta (written in 1958), Tolkien wrote that none of Mandos' dooms had declared whether the Marring of Arda would ever be repaired (CT adopted this passage and used it to close the Quenta Silmarillion). This shows that at least the Second Prophecy of Mandos had been rejected, and with it perhaps the Dagor Dagorath as well. There are some who believe the Dagor Dagorath may have been retained by Tolkien even if the prophecy was rejected.

Retrieved from "http://en.wikipedia.org/wiki/Final_Battle"

well ever wondered what would happen if morgoth escapes?

i found one nice story about that - http://www.fanfiction.net/s/2001002/1/

i just hope Luca will ever continue...

Oh, and now he is incarnated in Osama bin Laden.... *shudders* It really do sound like Morgoth is very much present in this world....