Sure. By no means would I call myself a strong Trump supporter (if at all), but I think it's very naive to say Bernie Sanders has an 80% chance to beat Donald Trump. I say that because you don't want to fall into the same trap that the media fell into when predicting the 2016 US Election with Hillary Clinton. Trump is now the incumbent, the economy is doing great under him, and he's kept many of the promises he pledged to (I stress especially the increase of manufacturing jobs because the Great Lakes area did vote for him, and narrowly he won the presidency because of them). You also have to note that the reasons Dems gained wins in 2018 is because they ran a lot of moderate candidates in suburban areas across the US, and that is an area where Trump admittedly needs to pick himself up. Bernie Sanders is pretty far left, whether you like that aspect of him or not, and going too far could push suburban independents into Trump's camp (which is the part of the population both candidates should focus their strongest attention to coming into 2020).
Going on to Electoral Strategy though, assuming Trump wins Florida again (which is leaning red), all he would really need to realistically do to retain the presidency is to keep at least two of the following: Wisconsin, Michigan, or Pennsylvania. Wisconsin recently held an election for a vacant state Supreme Court seat with surprisingly large turnout, and the conservative candidate won by a pretty fair margin. Admittedly, PA does have the chance of going back to blue given the slimness of the 2016 election and the Democratic wins there in the 2018 midterms, but they also just had a recent state election where they did vote blue. That is largely because the Democrat that won is a military veteran with blue collar appeal (aka a strong moderate). That's where I have my apprehension as to whether PA is starting to lean blue again or not. Michigan, however, is probably the strongest toss up, however, but once again, the economy and rise of manufacturing jobs (as promised) may keep them with Trump, but it is pretty uncertain right now.
If you want my honesty as to who has the strongest chance of beating Donald Trump, it's Joe Biden, largely because of that blue collar and suburban appeal (even with the #MeToo drama going on, which is kinda stupid but that's a story for another day). However, I do agree that Bernie is the strongest Democrat candidate going into the primaries. I strongly disagree that he has an 80% win rate though, and here's where I would amend that. I would put him in the low 50s in that I would edge Bernie (given if Trump loses one out of the 3 states in the trifecta I mentioned earlier, he's gonna be in serious trouble), but I think that contentiously it's gonna be even closer than 2016.