In mid-July we will learn who will run against Donald Trump. On current indications, it looks as if it will be Joe Biden. I bet Trump is hoping so.
I'm not a fan. He's too close to the corporate elite, and has a chequered history on women's rights (voted against Roe v. Wade, for example) as well as supporting cuts to Medicare and social security. As Sanders said yesterday, his presidency would be the 'same old, same old'.
The US needs a major political shake-up to limit corporate domination of both politics and the economy. Although Sanders would struggle to achieve much in that direction, he could still help to reverse the creeping authoritarianism that Trump is determined to implement.
As for Biden's chances against Trump: it will depend on corporate media and the state of the economy. If the media (predominantly pro-Republican) turns against Trump and throws its considerable weight behind Biden, he would have a reasonably good chance; otherwise it'll be four more damaging years of Trump's megalomania.