I would accept either option #1 or #3. But even if he opts for #2 and continues to be aggressive against Joe Biden, that doesn’t mean that Joe has to pay any attention to him. It seems to me that Joe is already pivoting away from Bernie and toward the main target, Mango Mussolini.
Joe can wait until Bernie flames out, to go and pick up Bernie’s supporters for the general election.
One thing that DOES concern me, is that option #3:End Campaign, doesn’t explicitly mention Sanders throwing his full support behind Biden. After what happened with Hillary in 2016, I don’t know if we can take it for granted that he will.
One option that has been raised:
Keep the campaign technically active with a goal of winning votes and accumulating delegates to the July nominating convention, but forgo attack ads aimed at delegate leader Joe Biden.
Another: Stay in the race and aggressively compete for the nomination.
A third choice: End the campaign.
The people with knowledge of the talks spoke on the condition of anonymity to describe sensitive conversations. They cautioned that other options or nuances may also be on the table and stressed that Sanders (I-Vt.) had not yet made up his mind and was still trying to reach out to supporters. A campaign spokesman did not dispute their account.
[...]
Before the coronavirus crisis, Democrats were anxious that disputes in the party would persist long into the general election, as they did after Sanders squared off against Hillary Clinton in 2016. That concern has only intensified as the pandemic has upended daily life across the globe, thrown the presidential race into uncertainty and created an urgent appetite for Democratic unity.
The entire article is well worth a read, as allies of Bernie weigh in on other alternatives open to the Vermont Senator.