I think another Obama type will be all it takes to crush Trump. Obama would have likely decimated Trump. Big contributors to Trump's win are probably a wholly lacking in charisma Hillary, Russia's help hacking and dumping emails of Democrats - spreading insane conspiracy theories and the momentum of wanting a 'change' from the current party.
Find another relatively young individual with the sort of charisma Obama had when campaigning and it should be relatively easy after four years of Trump disasters and scandals to oust him. He's not growing his base, which is already a minority, and the notion of him gaining more support seems far-fetched with how disgusted most people are with him. 70,000 votes went the other way in those those key areas and he would have lost. Shut down his Russia hole card of interference, stopping the fake news conspiracies is likely impossible, his crazified base is primed and loves that garbage. A focus on locking down against hacks and revealing the ugly internal machinations of political campaigns should be there.
The only way I see them losing is if they make a poor choice in candidate. Hopefully they pull through, or Trump ends up arrested/impeached, either one so there is no longer a deranged fool with that much power available to them.