From Morgoth's Ring (which was again, edited by Christopher Tolkien from his fathers unfinished texts), some among the Elves believe that there will be a New Arda rebuilt from the beginning without Malice, which the Elves will partake of from the beginning. It goes on to say that the elves believe that all of creation exists inside Ea and that they do not believe in "contemporaneous non-contiguous worlds" (seperate worlds existing at the same time; this being said, they don't deny the existence of other worlds, they simply don't believe in them). They say these worlds are unknowable, and if there are a rare intersections, they are still only provinces of the one Ea.
Morgoth's Ring said:In that region of Time and Place the Elves will dwell as their home, but not be confined to it. But no blessed spirits from what is still to us the future can intrude into our own periods of Time. For to contemplate the Tale of Arda the Blessed must (in spirit or whole being) leave the Time of Arda. But others use another analogy, saying that there will indeed be a New Arda, rebuilt from the beginning without Malice, and that the Elves will take part in this from the beginning. It will be in Ea, say they - for they hold that all Creation of any sort must be in Ea, proceeding from Eru in the same way, and therefore being of the same Order. They do not believe in contemporaneous non-contiguous worlds except as an amusing fantasy of the mind. They are (say they) either altogether unknowable, even as to whether they are or are not, or else if there are any intersections (however rare) they are only provinces of one Ea.