The answer is, it depends. My current answer is wait for other elected US officials to act. That's worked pretty well for hundreds of years. Somebody acts outside the bounds of the law, they eventually get removed from office, possibly put in jail, etc.
The nice thing about democracy is it's a structure that resists consolidation of power. If one person starts getting too much power, other people will use democratic mechanisms to reduce that power. It's not like the Republicans would allow George Bush to become a dictator, or the Democrats would allow Obama to become one, because then no one else gets their turn in 4 or 8 years. And consolidation of power means a Senator who used to be able to leverage his vote for consideration of his pet projects (or donors or whatever) doesn't want to find himself where he's only leveraging his vote to not get arrested. And all those corporations who finance political campaigns don't want to be in a position where a dictator can come seize their assets either.
And even the President himself doesn't have a whole lot of incentive to become a dictator - he's going to be rich whether he stays in power or not, so best not to get in a position where the only option people have of getting rid of you is killing you.
The idea that any single entity is going to consolidate power across 50 states, each with their own military and police apparatus, and with the cooperation of the members of our volunteer military, is just plain ridiculous.
What we're talking about here is a very sensational, but very minor, topic. More American citizens live or die on changes in DUI laws than the drone use policies. George Ryan (former Illinois Governor) killed more American citizens as a result of taking a single bribe than Obama has killed with drones.
Like all issues with what should, and should not, be legal actions by the government, this one will get settled through legislative or judicial process. We're not talking about the arrest, jailing, or killing of political opponents. These are people who have specifically declared a desire to destroy the political process entirely.