I sure don't love him stooping to the level of campaigning of Hillary Clinton, but I sure like it more than a Trump presidency. Go plead your case, Bernie.
When asked in March if he would campaign for Clinton and the Dems were he to lose the nomination, his response was, "Well, what are they going to do for us?"
Sanders no doubt had to be coaxed into this, and he will not disappear after Nov 8. Far from it. He will be regarded as the 'shadow Majority Leader', the standard-bearer for the progressive wing of the Democratic Party, and will remain vocal and visible through the Clinton presidency.
He has also, probably, secured assurances that the DNC will invest in organizing at all levels throughout the country. What those assurances are worth, we will see. As he well knows, he is dealing with professional liars.