Not to my mind, God has already stated what Satan's fate is, so I am not sure why anyone (except those who do not believe God) would have any other opinion.
Maybe some people have a God of their own imagination, and cannot imagine a sovereign God, who can dictate what is just, and what is right, and then carry out that justice, so they doubt that such a God really exists?
This sounds like a logical conclusion. I have come across material in the past that denies a sovereign god who can dictate what is just. Others might not deny the existence of god but deny the existence 'his' ability to know what is 'just'. For example looking at morality and sin as subjective thing - within the eye of the beholder.
But 'logic' like this denies the word of the bible in my view.