Well, at least this Princeton study seems to disagree with you that US is not already an oligarchy:
http://www.bbc.com/news/blogs-echochambers-27074746
When you have Congress listen to an infinitely larger degree to the powerful and the "will of the people" has a meaningless effect on their decisions, I think that pretty much defines oligarchy.
https://www.youtube.com/watch?v=5tu32CCA_Ig
And before you say "wait a minute - didn't we stop SOPA?", I remember an interview shortly after SOPA was stopped, with Darrel Issa, one of the two most aggressive politicians in Congress wanting to stop it (along with Zoe Lofgren), and he said that what got everyone else to change their minds about SOPA, too, was actually having the big companies join the fight and lobby against it - such as Google, and so on.
That's what apparently got Congress to change its mind about SOPA. There were millions of calls indeed, but a good chunk of those were pushed by Google and Wikipedia on their home page, so I think he's at least half right about that.
If you ask me, I think only two things can change the way the US is right now:
1) a more democratic and representative voting system (IRV/RCV seems good enough for mayors/governors/presidents, and multi-winner RCV/STV for Congress (as well as local councils, etc) would also fix the gerrymandering problem which is a huge issue on its own with American politics and would provide a more representative multi-party government - the end of the two-party system, in other words).
https://www.washingtonpost.com/news/in-theory/wp/2015/10/23/...
As long as the US has the FPTP voting system, people will keep voting for the "Lesser Evil", because they "don't want Mr. Evil" to win (whoever that may be). That's just a terrible way of electing someone democratically. People should have a system that makes them vote with the candidate they like most. Anything else should be thrown out. The FPTP is also what will help Republicans keep winning a majority in Congress with only 40% of the votes, as it tends to happen wherever FPTP exists. Also a terrible way of having a "representative democracy" (even if every now and then it will be the Democrats that will win 51% with 40% support).
2) campaign finance reform (time to end or at least equalize the "money vote", which right now greatly skews the "voting power" in the favor of those with the most money. The vote is supposed to be "equal", but the "money vote" is a sort of parallel voting system that skews who can win and who the winners listen to. Not very democratic at all).
I'm not sure which is more important, but I think the first one could pass more easily, and then over a period of years, people can start electing more representative candidates despite the money the "establishment" candidates will receive. And then those more representative candidates can start supporting changing the campaign finance system as well.
These two changes in the end should be enough to put the US on a more democratic path once again, and act as a catalyst to fix many other political issues, too, whether it's social issues, immigration issues, health issues, copyright issues, and so on.
There's only one candidate that supports changing the voting system (to IRV/RCV) right now (as well as real campaign finance reform), and that's Bernie Sanders (just FYI).