There are lots of signs that Biden is in control of the race at the moment, and as far as I can see very little signs that Trump will ever catch up in the popular vote. The question really is whether Biden will win in the key states. I can easily see a scenario in which Trump loses big in the popular vote but just sneaks the College. Which would be a disaster.
Still, here's a question for you, TTT: what incentive does Trump have to concede defeat if 2020 is going to be the "most CORRUPT ELECTION", "most RIGGED election", etc, in the US's history? I'd suggest that he wouldn't, or at least he would be extremely vocal about how unfair it was.
And don't give me the "it's just posturing" talk, either. Trump can insult Biden and Harris to his heart's content, as although we should demand better of our politicians than a playground slanging match it is somehow normalised now. But calling into question the integrity of the system (not to mention actively undermining it) is not posturing. See, for example, Belarus, or Russia, or any of the other many countries that are democratic in name only. Or think about what Johnson would have said had Corbyn somehow won last December. Answer: he'd have conceded defeat and left Downing Street the next morning. Shocked, perhaps (as would the entire country have been), but accepting of the result and of the system.