All that needs to happen to cripple the FDA is for the government to allow Prescription Drug User Fees Act (PDUFA) to lapse. That would mean the FDA wouldn't be able to collect user fees from drug companies for expediting approvals. Which would reduce the number of drugs coming through. It is also a major source of funding for the agency, and would cut drastically into their activities, including inspecting food and drug companies.
State-Level International Policy
When you think of international policy, I'm sure you think of the ability to sign treaties. But I'm talking specifically about immigration a possible slippery slope. If the federal government can't agree on a standard US immigration policy, then the states will take it on themselves. Arizona, for example, passed a bill that is targeted at curbing illegal immigration, and is on its way to the Supreme Court to hear whether it is constitutional. If it survives, individual states could use it to take international policy away from the Federal government, which is the rightful holder of those duties.
We've been at war for most of the past 20 years. The reasons why are debated, and I'm not going to get into them. But without the government working together, it's unlikely we will ever get fully out of the unpopular conflicts in the Middle East. A strong force keeping us involved is the inertia we've gathered during the military actions of the recent past. That inertia is reinforced by the stalemate in the government, because its almost impossible to get a large enough majority to do something dramatic, like end a war, with 100% die-hard opposition.
Immobile law makers or regulatory agencies put strain on our markets. And that strain is translated into volatile stock and bond prices, as speculators cause large swings in the value of market instruments. The market actually responds favorably to final action by the government, because that reduces uncertainty and calms risk. The less that gets done in the government, though, the more uncertainty there is as issues build up in the queue.
I'm not a doom-sayer. I don't think that the worst will happen in all cases. But I do think there needs to be a change in the political landscape so we can avoid some of the consequences above. What do you see as the biggest outcome of a fully gridlocked government?