I don't see tonight's debate as doing anything to change the trajectory of the nomination contest. Biden was solid and it seems doubtful that Sanders' umpteen-thousandth repetition of his basic talking points on inequality and fighting the the power of the rich will turn the tide.
So Biden it is and it appears likely that he will face a weakened Trump. The coronavirus crisis, unavoidably bad, is simply being made worse by his incompetence. And presidents inevitably get blamed for bad things that happen on their watch, especially if they perform poorly.
And then there's the economy. It's hard to see how the crisis doesn't tank the economy to some degree and Trump'll get blamed for that too. So an unusually weak incumbent is becoming even weaker.
It should be a favorable situation for Biden and his running mate. And who should that running mate be? We now know it'll be a woman. Klobuchar? Harris? Abrams? Warren? Whitmer? Your choice here?