[thou hast prepared a house for man]: There is a habitation created for the exalted man. This refers to any kingdom of glory (DC 88:21-24). At this point, Moroni makes no distinction in the various kingdoms. However, the reference here is clearly pointing to the concept of the many mansions in the house of the Father, as reported in John.
Reference: The points of connection between this verse in Ether and the verses in John include the concept of the house, mansions, and that Jesus has prepared the way for us.
John 14:2-3
2 In my Father's house are many mansions: if it were not so, I would have told you. I go to prepare a place for you.
3 And if I go and prepare a place for you, I will come again, and receive you unto myself; that where I am, there ye may be also.
In the Ether text, the difference is that the emphasis is on the function, not the place. In John, the place is the reward. In Ether, the place is the promise of celestialization that fuels our hope and faith. In Ether, the house is the goal hoped for, in John it is a promise obtained (or obtainable).