We have had demos for *decades* on engines and consoles and they never reach that point. Remember Agni’s Philosophy?
I do remember it. And I recommend people should watch
Agni's Philosophy (or watch it again if it's been a while,) as it's interesting to see how the technology demonstrated in 2012 translated over into aspects of Final Fantasy XV. The specs on Agni's Philosophy were significantly more than the actual final PS4 (that demo hardware was a GTX 680 with 16GB RAM, which is maybe more in the ballpark of a PS4 Pro, but Pro has still half that RAM,) and the level of fidelity and complexity was fittingly not up to Agni's level, but the core technology scaled down to work on machines of that generation. (Agni does have some crazy-pretty particles though, sure wish that was something these machines could have put out like that...)
(BTW, the later
Witch Chapter 0 CRY demo was an example of Square's "next"-next technology, getting into more current hardware implementations and experimentations, although given it was running on four GTX Titan X graphics cards, that's a lot to live up to even 7 years later.)
But yes, do be smart about understanding what demos are when you check them out. They are not games, and they are usually not demonstrated with consumer hardware nor under interactive conditions. Read the specs, read the project prospectus, learn the conditions and proposed applications, scrutinize the use under realistic conditions... and if all you are interested in is gameplay, maybe don't bother checking it out. But if you like this stuff, have fun!
