If Hitler was not a believer in Jesus (he didn’t have the fruit it seems) than he will not be given eternal life - he will die. He is not given immortality, he remains mortal - he will cease to exist. I don’t believe the Bible teaches ultimate reconciliation or universalism - the wages of sin is death, the gift of God is eternal life!
Your argument presumes a definition of death, which isn’t entailed by Scripture.
A better position is to identify death as a state of existence involving separation.
When he suffered the first death, his soul was separated from his body. With Adam, all men suffered a separation of their human spirit from fellowship with God’s Spirit.
When we become believers through faith in Christ, God provides us a regenerated human spirit with our body and soul, giving us spiritual perception in faith which is His work.
The soul continues to exist after the body physically dies, and the body continues to exist, although then separated from the soul and spirit.