I have been thinking about eschatology lately and have decided that it's a mystery. We don't have enough to go on to know when Gotterdammerung will come about or what it will look like. Maybe we won't even know that it has happened. One day we'll be plugging away as usual and the next thing you know we're living in the Kingdom of Heaven.
I'm not afraid to speculate, and I have some eschatological suspicions that I'll share now for what they are worth. I have not had any special revelation from God, nor am I trained in theology, but I do have some completely irrational beliefs about our ultimate fate that I reckon are as authoritative as anyone else's.
Judgment Day is billions or trillions of years away, and we will have become a class 3 or better galactic or intergalactic civilization by then. The teachings of Jesus, as practiced by those who actually understand them and in whom the Spirit dwells, will be the characteristic of humanity that permits us, among all the intelligent species in the universe, to avoid destroying ourselves and to go on to the next levels of civilization. Our technological advancement will go hand in hand with our ability to love. Love will inspire us to occupy the whole universe. We will be a blessing to the universe, and the Kingdom of God will encompass everything.
Earth will be long gone by then, and I can't imagine what kind of beings our descendants will be by then. They may not even be flesh and blood.