As we've seen plenty of times in the movies, the death of a Force-sensitive individual does not necessarily mean the end. The soul, or essence, of these powerful individuals remains, and although they cannot participate in the world physically, they can still interact with the living. Is it possible Snoke is the Force ghost of a powerful figure we've seen before? For instance: Palpatine/Darth Sidious, or even Darth Vader himself.
The big problem is that Force ghosts are in a sort of "in-between" state, and they can't stay there for long. It would be hard for a Force ghost to rise to such power. And furthermore, it would make for a pretty lame reveal if Snoke was a villain we've already seen defeated.
So, what do you think? Do you buy any of these theories? Do you have one of your own?
