Trump seems to be maintaining a 50% approval rating despite tons of negative press and likely even the polling organizations hate him. He continues to draw huge crowds at all his events. I haven't heard of that happening at any of the Democrat event. IMO, unless something completely different happens over the next year, he will win a second term easily.
Unless this impeachment stuff actually digs up actionable stuff, I don't see anything happening. Impeachment and Russia and "Name That Scandal" has been the big headline for 3 years since before Trump took office. Do any of you really think something is going to come up now? I would think the odds of a physical attack on Trump are higher than the odds for impeachment.
It really is very early and no one knows for sure what will happen until states actually start voting in the primaries early next year. IMO, someone like Tulsi would be a more effective candidate against Trump than Biden or Warren. Lots can still happen though.
I would add that so far the Economy is still doing well. That generally favors the incumbent.