Wink wrote a pro-Bernie essay that I mostly agree with.
Chris Hedges wrote an anti-Bernie essay that I mostly agree with.
Just like Donald Trump is important, but still mostly a symbol of a larger problem, we shouldn't get hung up on Bernie Sanders.

Bernie never intended to overturn the corrupt system. Like FDR before him, Bernie sees his job as saving the existing system from itself. His intentions are noble and helpful, but even Bernie underestimates how broken the system is.
Nevertheless, and here's the important part, Bernie Sanders is necessary. Absolutely, unquestionably necessary.

If I was to compare Bernie Sanders to a historical figure, I would maybe choose Francisco I. Madero, who started the Mexican Revolution in order to reform and save the existing system, before he become a victim of events (and a bullet).

Bernie has filled the necessary role of opening up the Overton Window.
Previously forbidden words like "socialism" are no longer taboo.
Even more importantly, Bernie forced the establishment to show their hand and to openly rig an election against him. Thus shaking the faith of millions of Americans in our phony democracy.

Someone had to do this before any real, substantial change is possible.
For that we are all indebted to Bernie.

What comes next is the long overdue effort to reform the system.
This is also an absolutely necessary step. It has to happen, no matter if you think the system can be reformed or cannot be reformed.
No substantial change can happen without this step happening first, because even if the system cannot be reformed, that fact has to be proven to the general public before they will embrace anything more radical.

Can the political system be reformed? Neither you nor I know.
I have my doubts, but it can't be ruled out. If South Korea can do it, then it's possible here too. But that doesn't make it likely.

How long will the effort at reforming the system go on? It's impossible to say, although we'll certainly still be in the reform stage in 2020.
Much of this depends on the economy, which may be about to roll over. A full 40% of the population is barely hanging on, and that's too many people to passively accept starving to death.
Think of the food riot as a revolutionary indicator.

The next recession will create a crisis in the Republican Party.
Almost all of the Republican areas are depending on Trump's promise of economic growth, while the Republican establishment fully intends to gut what little of the safety net that still exists.
That means a lot of desperation for a lot of already angry people.

If you want the system to change, then you'll want Bernie to run in 2020, because the Dems will never allow him to win (again).
The Dems will almost certainly be more subtle about cheating Bernie next time, but the end result will still show the bankruptcy of the Democratic Party.
Thus 2020 will create a crisis in the Democratic Party.

Only at this point, after 2020, will a third party have a real chance.
Lots of other darker and more dangerous things will also have a real chance.