Le my opinion:
Welp I guess we should get our salutation technique on point for when Mr. Trump becomes President Trumpler. However, if democratic voters are less self-centric then they have been in past elections and actually decide to vote even though their candidate of choice *cough sanders* doesnt win the primaries, Clinton can probably win 60/40. And she's married to one of the better US ex-presidents on top of her own above-par political skills, so she's definitely the lesser of all evils, despite her being, in my opinion, a corporate slave.
It's worth remembering that heaps of Clinton voters said that they wouldn't vote Obama in 2008, but by time time the election rolled around nearly all did. I suspect it will be the same with many in the 'bernie or bust' crowd. That said, it's a small crowd - exit polls generally show that a large majority of Democrats would be perfectly happy to vote for either candidate. On top of that, it's always worth remembering that Clinton is winning by every metric (national polls, total number of votes, total delegates, etc).
That said, if Sanders is serious about stopping Trump, he needs to drop out of the race immediately and give Clinton the space she needs to take on Trump (or, at the very least, stop attacking Clinton personally).
At this point it's really important to remember that the general election (and general electorate) is vastly different to the primary election (and electorate.) Trump was in a 17-person free for all at the start of the Republican race, and was very effectively able to use the media to rise above this, get attention, and get momentum early on. He got it to the point where it was effectively Trump vs. Cruz, and plenty of Republicans couldn't stomach Cruz. In the general election he won't be able to do this. It will be 1v1 Trump v Clinton. He's also lacking the backing of his party establishment (Republicans on Twitter have been coming out in droves to support Clinton) and he'll have trouble raising money. General election campaigns are very expensive, and it's not something that Trump will be able to bankroll personally. Many Republican super-PACs are abandoning Trump (remember plenty of them were running anti-Trump ads), so he'll have trouble getting the money he needs. Clinton, meanwhile, will have no problems.
Anyway, hold onto your hats. This will be a fascinating election - down with the elections of 1860, 1912 and 1980 as great elections in the United States. I'm a bit disappointed that we didn't get to see a contested convention, though.