I’ve seen (ummm…certain types of) where the face of a celebrity is superimposed over someone else’s body. Its very, very realistic except when it occasionally glitches around the edge of the superimposed face, especially when something, like an arm passes in front of the face.
Standby for Gemini Man.
Dang lingyi!
“I’ve seen (ummm…certain types of) [NSFW videos] where the face of a celebrity is superimposed over someone else’s body. Its very, very realistic except when it occasionally glitches around the edge of the superimposed face, especially when something, like an arm passes in front of the face.”
Also, I just found out that Deepfake (thought it was a specific group’s name) is the name for these types of videos. Do a search on YouTube for them. Most aren’t as convincing as the ones I’ve seen. No doubt because of the lack of umm…distractions. 
The obvious is “anything that relies on more than the I part of CGI”. One example that springs to mind is memories/dreams, which typically feature sounds, smells, physical sensations, moods & emotions & more complex stuff (like existential dread, or the absolute knowledge that there is something dreadful right behind you) that a computer or screen simply cannot simulate. Yet.
Ah, the Recently Vegan Model 
Still images are a snap (scroll down to page 9); full body with animation isn’t far off IMO.
Technically, hair and fur have been the most difficult things to get right. From the looks of the latest Lion King, they’re getting really good with fur. But realistic long hair is still a difficult problem.
Oh yeah, that network knows how to do a face, but it doesn’t know much else. The backgrounds can get pretty crazy, and if there’s a hand in the shot it looks like a Francis Bacon painting.
I don’t think there is anything they can’t do currently given sufficient time and money.
It seems to me a lot of the comments are based on not seeing things done well in certain movies, but that’s often due entirely to budget and time restrictions placed on the animators.
As far as CGI people being in the “uncanny valley” in 2019 - did anyone watch Avengers Endgame? Captain America’s aging at the end is all CGI, no makeup was used at all. I couldn’t tell it from real life. (“Fat Thor’s” body was also entirely CGI)
I’d also guess all of the fire & explosion scenes etc were CGI too.
They can do anything now.
But that was still CGI applied to the real Chris Evan’s face, doing real acting and speaking and emoting. Creating a face from scratch, and having it behave like a real human face, is more difficult. What they did is impressive, to be sure, but it’s not the end of the line.
Birdemic: Shock and Terror demonstrates that CGI still can’t convincingly simulate the actual explosions that occur when birds hit the ground. I was not fooled for a minute. They should have just filmed the real thing.
Have they made huge strides since Tarkin in Rogue One? Cause it certainly wasn’t there yet then. When they have a CGI human character THAT prominent in a movie and it 100% works, then I will say no, there is nothing CGI can’t do.
I will say I found the CGI in The Lion King utterly convincing. They certainly have nailed animals and landscapes.
It doesn’t seem good at dealing with glasses on the face either - in a few refreshes I saw someone with the front part of glasses removed but not the side pieces, and at least one where there was a blur in a spot that was most likely improperly removed glasses.
God.
When you look at CGI Tarquin in Rogue One, and Tarquin in the original movies, it’s quite clear that one of them looks just a little bit too freaky to be a real human.
Unfortunately for that argument, though, the freaky-looking one is Peter Cushing.
My brother is a CGI tech. He once did some fire about 15 years ago, and got a note back that it looked “too hot.” He wrote back “What the heck does that mean?” and they responded that the fire was “Too realistic.” Apparently the whole point of CGI-ing the fire was to have magic fire, or something. He gave them magic fire, and they were happy.
Again, this was about 15 years ago, but at least at that time, it was apparently easier just to burn something and film it if you wanted fire, and the only reason for CGI was if you wanted your fire to be somehow “otherworldly.” Or you wanted the bush not to be consumed, or whatever.
This may still be the case.
Also, my brother says that people want to see real people in movies, particularly dramatic movies, most of the time. It’s easier to relate to them. He says that human actors aren’t going anywhere.
Fire in movies isn’t usually CGI, because it’s so hard to do realistically; instead they film elements of real fire and composite it on. The problem with that is it doesn’t have true volume or react quite as realistically as you might want. See Crowley’s burning car in Good Omens as an example of that.
Aircraft flying realistically.
They can make CGI aircraft that fly realistically; they just choose not to.
Spacecraft flying realistically.
Oh wait a minute, that’s another “choose not to”.
Nitpick: Tarkin.