Forget installing a shah of Iran or propping some dictator in a South American country. They can now do the same at an arms length. Just collect dirt on all foreigners, wait until they get into power, then use whatever dirt you collected over many years to blackmail that person to do things that are in the self interest of the people at the NSA instead of the self interest of the people that duly elected that representative.
This whole situation is a legitimate threat to democracy in this country, but Congress may try to put checks and balances in place to slow the rate at which it erodes democracy at home. However, of more immediate importance is how this is a legitimate threat to democracy everywhere outside the US.
Many Americans may hear the NSA say things like "We don't do anything illegal and coercive with this information at home" and may believe them. But do most Americans think it is reasonable to coerce elected officials or other countries using any information gathered by the NSA? Should we not be asking the NSA if they actually do that?
This is one of the questions I most want to see asked:
"General Keith B. Alexander, has the NSA ever wittingly used collected information on any foreigner elected to office by his or her citizens to coerce or blackmail that duly elected official to pursue policies that may not be in the interest of the citizens that elected them?"