"is hinging on" is correct and usable in written English.
You can use it to refer to a situation or decision that is contingent upon a certain factor or outcome. For example, "My decision to go to college is hinging on my grades this semester."
This opposition is hinging on the broken tax promise, but is actually far more complex.
"A lot is hinging on the Clinton visit and what comes after it".
The presidency is hinging on a bunch of very tiny and peculiar variables in the Sunshine State -- I'm waiting for reports of voter fraud in the Magic Kingdom.
Much is hinging on the Nokia release in the third quarter of its N8 smartphone, the first device running the company's Symbian 3 operating system, which has been improved for touchscreen phones.
The operations, which began in late April, marked a new phase in the American-led war in Afghanistan: The conflict is no longer being decided by precision bombs and large-scale infantry operations, but instead is hinging on American, British and Australian commandos mounting a counterinsurgency campaign.
That means a lot is hinging on the next few quarters and whether this coming IPO boom materializes.
"But I've been moving away from doing things where success is hinged on my face being stuck on things.
He believes democracy is hinged on a free press and that depends on there being a professional press".
She is a developer of a boot that is hinged on the inside and outside of the ankle.
The book is hinged on this notion, which presents itself through the revelation of a family secret.
I could see the extent to which our society is hinged on the written word, and it turned me into a bit of a fighter.
