The reason why Assange stayed in the Ecuador embassy for all those years was because he was afraid of, and had every reason to believe England would extradite Assange to the US. As long as Assange remains charged in the US, I do not see any way he will not be extradited to the US based on the
treaty between the two countries.
After the 2020 election, Trump should pardon Assange. Assange has embarrassed many powerful people in DC, and Trump will not have political support for doing this. Depending on his margin of victory, and the state of Congress after the 2020 election, Trump may need to wait until after the 2024 election.
Honestly I don't think this is something that is going to happen, Trump may like Assange personally for what he released and such -- though the Republican party isn't going to be able to allow him to walk for what he released regarding the War in Iraq / War on terror that was released in 2011 (I think) by Assange. This is also the time when Democrats LOVED Wikileaks.
If Assange was simply releasing information, like media companies in the US do time and time again -- that's one thing. Though if he has helped in actually hacking databases, paying people to do it, and so on -- then he should be punished as such.