And I appreciate that viewpoint too. People have been under-estimating the Trump campaign in both parties and it is evident that the more free press he gets, the more the worry of a Trump Presidency becomes a real concern and hard to throw money at. Both Hillary Clinton and Bernie Sanders polling numbers show that in a head to head competition, they can win, but at the moment, it depends on which numbers you look at and whether you believe that they will hold currency when November rolls around.
For that reason alone, I say let the Democrats play this out to the conclusion and see what happens between the end of the primaries and the Convention in Philly. There are a lot of cards to be played, not the least of which is unifying a fairly frayed party. I firmly believe that the Democrats who are accused of having to love their candidate, can still fall squarely in like with whomever is selection. But how this happens depends on some factors, for instance:
1) The role of the DNC at the convention. Clearly there is a rift between party Centrists and the left-leaning wing that Sanders seems to have built up. Debbie Wasserman Schultz is a lightening rod for a significant number of party members, but she has also be the spokesperson for the party. If it is seen that she is being thrown under the bus for unity and Chuck Schumer replaces her as scheduled, then things may not go well for Sen. Schumer, who is seen as another Clinton surrogate. On the other hand, if it becomes a battle royale between a Sanders leaner and Sen. Schumer, that doesn't help either.
2) If he does not win the nomination, significant face time for Bernie at the Convention and his tone in using his time will be closely scrutinized. If he begrudgingly is conciliatory or, as he has promised, backs Hillary Clinton fully and encouraging his followers to do as well, it will help. Likely as not, those who closely follow Sanders will join him, even though some younger or more skeptical may see him as then bought and paid for, if he does toe the line.
3) Choice of running mate by Clinton or Sanders will be important. It is not very likely nor advantageous for the eventual candidate to choose his or her rival. A fresh face or a highly esteemed neutral party will likely needed to change the conversation. There are lots of names bandied about, but if it is Sanders, he'll need either a progressive who is seen positively by Clinton's supporters and vice-versa for Clinton should she chose a more moderate running mate.
4) Focus on the prize. Whoever the next president may be, she or he will be naming at least one member, but possibly two or three more in their term. With a fractured military and unfocused foreign policy goals, a coherent policy must be constructed. And on top of that, living up to campaign promises will, be "yuge." Donald Trump in some ways is the least of their worries, but in the immediate space, must be dismantled in a unified way, but that will become more difficult as alliances on the R side are better formed.
There is not a real other option for the Democrats in terms of timeline. The will have to slog it out and get their house in order both in the backroom and in public at their Convention in Philadelphia. It won't likely be very pretty, but thankfully the finish line stretches further than November.