Very few programs will throw you out on the street. I've heard of a few people that got their PhD's eventually for passing go enough times. It happens.
They don't throw you out on the street - they just cut your funding or string you along.
One story I heard about a physics PhD candidate at UCSB (this isn't me, I wasn't in the physics department). A MechE prof he worked with stole his research and got a tenure track offer at another school, leaving him behind. He was living in his car for a while and was a paintball aficionado. One day he happened to pull up outside KITP just when some of the more senior professors were walking by. He, in a disheveled state, opened the car door and mounds of paintball ammo spilled out. Looks were exchanged, emails were sent and phone calls were made, and he was PNGed from the campus soon after.
