The Watchtower has never said there will not be opposers who prove unrightous in the new System.
Crime, violence, and wickedness will be gone forever. "Evildoers themselves will be cut off ... Just a little while longer, and the wicked one will be no more ... He will not be. But the meek ones themselves will possess the earth." (Psalm 37:9-11)
All who oppose God's Kingdom and who are part of Satan's wicked system will be eliminated. Only those loyal to Jehovah will survive. -Revelation 7:9, 14; 19:11-21.
Perfection! What will it mean? It will mean a return to life the way Adam and Eve enjoyed it before they sinned against Jehovah God. Physically, mentally, emotionally, morally, spiritually -in every way imaginable - perfect humans will fully meet God's standards.
Promises such as 'wickedness will be gone forever' and 'the wicked one will be no more' certainly sounds like their i mplying Jesus will only r esurrect those who are rightous in this 'wicked system' then during the thousand year reign, all sin will be removed and mankind will be raised to perfection.-1 John 2:2; Revelation 21:1-4.
"There is no man righteous in the earth that keeps doing good and does not sin." (Ecclesiastes 7:20)
So as all sin will be removed all the people will not sin therefore they will be righteous and keep doing good.
As Jehovah is perfect he must have perfect standards if perfect humans will fully meet God's standards im sure one of God's standards is for no one to oppose him. but im sure the dubs will have some excuse its down to humans 'free will', etc..