After the 2020 election, Trump should pardon Assange.
Why would Trump do that? (Serious question)
As mentioned, pardoning Assange will be politically unpopular. The best time to a politically unpopular move is immediately after an election because you are maximizing the time until you need to face voters again.
If Trump wins reelection, and only has a narrow majority in the house and senate, he might wish to wait until after the 2024 election because pardoning Assonge might inspire enough Republican congressmen to be upset enough so they become opposed to Trump's agenda.
Meh, it still doesn't seem like a good reason. Why would Trump pardon the guy, that is definitely gonna keep digging under US government and sabotage his job? On one side we've got some mysterious inspiration for congressmen and on the other side we still get a real threat. I think their choice is obvious.
Trump does not need anyone's permission to pardon anyone. His problem is that if he pardons someone that many congressmen are opposed to receiving a pardon, they may stand in the way of his agenda out of spite. This is why many presidents pardon many people after the presidential election in which they are no longer up for election in; lame duck sessions are often very unproductive, and he will not be harming his party in an election.
Ignore that Manning was pardoned by Obama...
I don't think Manning would have gotten his sentence
communed if he had not been a trans.
Assange, right out in the open, tipped the 2016 election in the direction of Trump.
This is partly why I believe Trump will want to pardon Assange, in addition to it being the right thing to do. I think trump knows an Assange pardon will be difficult politically, and is hoping the SC will throw out the charges and/or conviction on first amendment grounds.