If Sanders has a path to a win it's going to pass through NY, CA, and WA. Last year (I think) all three of those states voted on Super Tuesday; this year their primaries come much later. This gives Sanders a chance to make his case and win over voters (and is a good example of why I oppose a national primary day). It will be very interesting to see how NY votes in particular. Technically, it's Clinton's home state but Sanders grew up in New York and is well known in upstate NY due to his work in the neighboring state. If Sanders manages to beat Clinton in NY then that's going to set the Democratic Establishment back on its heels.
Right now the most important part of that DE is the superdelegates. They form a large chunk of Clinton's current lead but they can be convinced to switch. Obama did this to Clinton eight years ago and Sanders could do it again. In theory, these delegates are not locked to the primary vote but are supposed to help the party pick the most electable candidate. The Sanders camp are going to spin a story that Sanders beats Trump but Trump beats Clinton, particularly if those anti-establishment factions that are backing Sanders switch parties to vote for Trump. So far national polling isn't supporting that story, but stay tuned.
Over on the Republican side, Trump made good progress but Cruz picked up enough delegates to continue looking viable. Rubio keeps talking about Florida but he has to be engaged in a very bad calculus. If he puts all his chips on Florida and loses that could be the end for his political career (see Al Gore). He's still young and might decide that it's strategically wiser to bow out now rather than risk it. FiveThirtyEight is currently summarizing the polling with Trump having a 73% chance to win Florida. If I was Rubio I would not roll those dice, but I also do not see an exit strategy for him that doesn't involve him looking like Trump bullied him out of the race. I don't know if it's in his character to back down in the face of how badly his character attacks on Trump have failed, or whether he'll need an actual electoral defeat.
Despite Trump's roll he still has a hard road ahead. Projections I've read say he'd need north of 65% of the remaining votes to ensure he went into the convention with a clear majority. He's currently polling at 48-49% and Cruz is arguing that Trump is slipping. I'm not yet convinced, but I would also not be surprised to see Trump continue getting 45-48% of the primary votes, well below a mathematical lock-in. Cruz's increase, if any, seems to have come from the anyone-but-Trump camp realizing Rubio is a sinking ship and abandoning him for (hold your noses, voters) Ted Cruz.
The spectacle of the Establishment getting behind the Tea Party darling whose egomania nearly shut down the government and gave the party a PR black eye is... epic. There's also a lot to be said (no matter who wins the election in November) about how the Republican Party got so very out of touch with the American electorate that it could produce a field rich in candidates and not a single one resonated with the primary voters. But that's future soul-searching.