1. One simply cannot film the story. It is not possible.
2. One can do it, but one should not.
3. One can do it, but the movie would flop because most people just wouldn't get it.
I'm not sure how much falls into category #1 these days. Telepathy? You can do it with voice overs. Special effects? Anything we can't do live can probably be done via CGI or animation, I would think.
What literally cannot be filmed these days?