"fall still" is correct and usable in written English.
You can use it when referring to something coming to an abrupt end. For example, "The usual hustle and bustle of the city had suddenly fallen still."
He was in free fall, still trying to believe that he was only in a dream of falling.
You may fail, but fall still fighting.
Trousers I'd owned for years would fall, still fastened, to my ankles.
Her fall came from such a great height, and she had very far to fall still.
Now that winter has passed, seasonal demand will fall still further.
Many of those who had found government work in the fall still hadn't been paid.
That means that a child who went unvaccinated upon entering kindergarten in fall 2015 because his parents opted out could have continued in first grade this past fall — still without vaccines.
Mr. McCabe, is the agent who is in charge of this very important investigation into Russian attempts to influence our election last fall still in charge?
"I begin by researching an idea, and never know where it will lead," Ms. Antoni said last fall, still in the Chinese-hemp phase of the project.
The Bonneville, which went on sale last fall, still has Coke-bottle lines and cat's-eye headlamps, but its tail is more upright and the taillamps are larger.
If surveys of Occupy Wall Street supporters conducted last fall still hold true, the crowds of protesters expected to turn out Tuesday for May Day events across the country will most likely skew male, young, white, college educated, underpaid, and thoroughly disgusted with the American political system.
