Anyone imagining Assange will only face 5 years during a fair trial on a charge of hacking is kidding themselves.
In 2012 Obama signed into law the National Defense Authorization Act which included a provision allowing a US president to order the indefinite detention, without charge or trial, of any person within the boundaries of US the president decided was aiding or abetting terrorism.
Under this law, the president can also order the execution of any non-American citizen anywhere in the world if the president decides that person is aiding and abetting terrorism.
I would not be at all surprised if Trump orders Assange to be indefinitely detained. That is, if he lives long enough to be extradited: he isn't an American citizen, so Trump can legally order his assassination. I'm sure his death on British soil would create consternation, but does anyone imagine Trump would care about that?
Indefinitely detained or legally assassinated, Republicans won't protest because of Afghanistan, and because of the DNC, Democrats won't either. The US will be a few steps further down the road to hard totalitarianism, and no one will ever leak anything again.
As far as the question regarding how the US could pressure Sweden or Ecuador: I think the question reveals a real misconception regarding just how powerful America, even in decline, still is. The dollar is the world's reserve currency, and America is sovereign in her currency. In practice, what this means is that the US can have enormous effect on another country's economy. For instance, In the wake of the 2008 crash and during the Greek crisis, it was US dollar swap lines with Brussels that kept the Euro from collapse, and those swap lines stayed open for years, with the US Federal Reserve buying excess Euros to keep the Euro from losing value, until the situation stabilised, then selling them back to Brussels.)
That kind of thing can work the other way around, though. A country that can keep another currency afloat can also crash it.