Consider Isaiah 65:17-25, which speaks of a historical era of a new "heavens", which means a new government, and a new "earth", which means a new social order. This passage portrays mortal life on the earth subsequent to the Resurrection.
In the Resurrection, the Justified are raised from the dead and transformed from mortal, corruptible creatures of the Natural Realm into immortal, incorruptible spirit beings. The Resurrection is the process of spiritual birth, whereby the Justified are born into the family of God as Sons. These Sons populate the offices of the Kingdom of Heaven, John 14:2; they are the officials who, under the King, Christ Jesus, govern the Earth forevermore.
Following the Resurrection, mortal life continues on earth, in the cycle of birth, growth, labour, reproduction, and death. However, because of proper government, the quality of life is improved greatly. Men no longer fear crime or the oppression of Caesar; warfare is unknown; pollution is not tolerated; many dangers are eliminated. Consequently the lifespan of mortals increases greatly.
In the King James Version, Isaiah 65:20 reads, "There shall be no more thence an infant of days, nor an old man that hath not filled his days: for the child shall die an hundred years old; but the sinner being an hundred years old shall be accursed."
The verse is saying that death in infancy is unknown, and that men typically live to what may be termed "a ripe old age". A man dying at the age of a hundred years is considered but a child, his death being the consequence of sinfulness. The implication of all this is that a man who lives an upright life may expect a lifespan on the order of a thousand years.