You should read verses 25 - 36 to see what Jesus was saying
Satan will be cast out of heaven but it has not happened as of yet , in Rev12 is when it happens
25 Anyone who loves their life will lose it, while anyone who hates their life in this world will keep it for eternal life. 26 Whoever serves me must follow me; and where I am, my servant also will be. My Father will honor the one who serves me.
27 “Now my soul is troubled, and what shall I say? ‘Father, save me from this hour’? No, it was for this very reason I came to this hour. 28 Father, glorify your name!”
Then a voice came from heaven, “I have glorified it, and will glorify it again.” 29 The crowd that was there and heard it said it had thundered; others said an angel had spoken to him.
30 Jesus said, “This voice was for your benefit, not mine. 31 Now is the time for judgment on this world; now the prince of this world will be driven out. 32 And I, when I am lifted up from the earth, will draw all people to myself.” 33 He said this to show the kind of death he was going to die.
34 The crowd spoke up, “We have heard from the Law that the Messiah will remain forever, so how can you say, ‘The Son of Man must be lifted up’? Who is this ‘Son of Man’?”
35 Then Jesus told them, “You are going to have the light just a little while longer. Walk while you have the light, before darkness overtakes you. Whoever walks in the dark does not know where they are going. 36 Believe in the light while you have the light, so that you may become children of light.” When he had finished speaking, Jesus left and hid himself from them.
To reign with Christ now means that if we stay with Christ he will empower us to resist sin and temptation , but since we are still in this carnal human body we are still subject to those things.
If a person turns away from the faith and Christ they will no longer reign with Christ but when in Rev 20 says we reign with Christ it is in a immortal body
When we reign with Christ we will even reign over angels , mankind has the intended purpose to be above the angels , angels cannot be redeemed when they sin
When satan is thrown down to earth it is then the Man Of Lawlessness comes who will be the person who Christ will throw alive into the lake of fire
Jesus is the Almighty God the Alpha and the Omega the Beginning and the End
He had forsaken some of his divinity when he came to earth to be the sacrifice on the cross; Jesus said that no man can take his life but he lays it down of his own accord because he has the power to take it up again
Jesus has never lost His reign over ALL things he came to take the sins of all the world upon himself so that we now have the path to follow Christ and be redeemed through His blood shed on the cross
