America's well on its way to this system right already. Congress and the executive branch cancel each other out when they're controlled by different parties, so nothing Congress passes gets signed by the president, and the president rules by decree with executive orders that can be overturned by the next administration.
Federal drug laws haven't actually changed on paper, individual presidents have just selectively decided to stop enforcing federal cannabis law against several states. Personally I'm in against cannabis prohibition, but this is a bad legal precedent to set.
If the US wants to end the drug war, it needs to actually pass a bill to change the law. Depending on the whims of individual presidents and their justice departments isn't sustainable in the long run. It also sets a horrible precedent of "nullification from above" with the executive branch de facto legislating by choosing which federal laws it will enforce. If the president can decide his justice department won't enforce federal law in colorado or washington, what keeps a president from deciding not to enforce provisions of the civil rights act or any other federal law?
If the results of an election are disputed between a party that win the electoral college and a party that wins a substantial portion of the popular vote, a charismatic general may decide to announce a "temporary caretaker government" by the joint chiefs of staff in order to prevent a civil war between the competing political parties. This could look like Poland under Pilsudki with a legislature that still exists but doesn't have any governing power. If the federal bureaucracy refuses to cooperate it could make the country ungovernable Kapp-putsch style, but if it decides to cooperate the bureaucracy is large enough to run a lot of functions on autopilot.
What if a president is set to step down after two terms, but the election for their successor delivers no clear winner. The next president would have to be decided by Congress, but if no candidate has support from a sufficient majority in Congress, the incumbent could be a "lame duck" president for several years where their term has officially ended, but no one has been chosen to replace them yet.