Though Hillary Clinton is way ahead in the delegate count at this point, this election cycle has proven already that even far-fetched scenarios can become reality. Should Clinton be indicted over the email issue, she might be barred from becoming the Democratic nominee, and then Sanders would likely get the nomination. Even if she isn't indicted, it's still mathematically possible for Sanders to win enough delegates to overtake her, too. His supporters are very committed to seeing him be president.
Bernie Sanders has been winning all the major races and new results are coming in everyday, awarding him new votes, new delegates and recounting votes that were tossed out or changed. It's been going on and it will continue to go on until the end. Conversely, Sanders supporters are fueled, not by idol-worship, but by the ideas whose time has come.
There is absolutely no chance that Sanders does anything at the convention. He cannot get the delegates as nobody truly wants to see him in office. He makes many promises but offers very little of substance as to how he is going to operate the government by giving everything away for free.
Sanders is planning to run a strong race against Clinton in the June primaries, and continue to the July convention even if he doesn't win the primaries in California and New Jersey, two political strongholds. It seems Clinton is on the verge of securing the Democratic nomination, She needs only 73 delegates to secure the nomination. As the situation stands, Clinton has a greater lead than any of her contenders. Sanders will continue to campaign, and rely on the strength of his previous wins, arguing why his party is better than the Republicans, to carry him further.