I think there are plenty of people in Fox News who have been willing to play fast and loose but still have their red lines. They're looking at Trump trampling (Trumpling?) all over them and realise it's beyond what they can tolerate.
I found this to be an interesting insight into what a Fox News journalist can be:
It's Megyn Kelly, ex-Fox News, strongly conservative, but no one's fool:
During Thursday's presidential debate, Kelly pressed Trump about misogynistic, sexist comments he made in the past, such as calling some women "fat pigs, dogs, slobs, and disgusting animals."
Trump slammed Kelly, saying her questions were "ridiculous" and "off-base."
"You could see there was blood coming out of her eyes," Trump told CNN's Don Lemon on Friday night. "Blood coming out of her wherever."