You couldn't make a sequel to The Matrix because it shouldn't be made.

Any Will Smith movie.

You couldn't make Casablanca today because that movie already exists.

You couldn't make Taxi Driver today, because Travis would have already died by suicide in a school shooting before reaching adulthood and getting a job. Plus watching Travis's nihilism growing not out narcissistic disgust with the seedy underbelly of New York, but out of love for the seedy underbelly of 4chan, wouldn't really have the same kick to it.

Scully and Mulder often had to clarify "they were in an area that did not get great cellphone coverage" thirty years ago, they were always getting separated in urban settings