This "eradicated from existence" part, I do not agree with because it sounds like the Jehovah Witnesses' doctrine of annihilation. When God creates the new heavens and new earth wherein righteousness dwells after the millennial rule, there will no longer be sin and death, crying or pain because all has been made new. But those that have gone to hell along with the devil and his angels, the anti-christ and the false prophet, will suffer for eternity, there is no eventual ceasing to exist. To say it that way almost sounds like the point of reincarnation for the Hindus and Buddhists. Their eventual prize called nirvana, is "becoming one with the universe", ceasing to exist and no longer having any consciousness of individuality. Perhaps this article meant something other than "eradicated from existence"? They will still exist, just not in any way that can ever again effect the new life with God.
I don't think Jack Kinsella believes what the Jehovah Witnesses believe :). I think he was just saying that, at a point in time, both sin and those who practice it and refused Jesus' offer of salvation will no longer be on the earth.
Their souls will live forever, as we know, they just won't be here. They will be in the place God created for those who want nothing to do with Him.