That is a good question, but it is a life boat case (a very rare situation that is almost impossible).
My answer is that Hitler would not receive salvation in this case.
- Because his heart is not authentic. If he left the choice of a Salvation prayer for the last minute before he died, he would not have had true repentance of his acts.
- She also would commit a very horrible sin right before his death: would be killing himself. Therefore making him not saved, again.
- He has blood on his hands. Christian or not, Hitler would have been responsible for the murder of millions of people. Even if he was "saved", I think he would still have to account for his actions throughout his life. There for being guilty of murder.
This is not a good example to explore salvation. It is a life boat case and does not apply to the majority of people in the world.