The immediate future for the Democratic Party, like the immediate future for the nation, looks somewhat gloomy. The total House popular vote has a record of swaying enough to get a Democratic majority, but the post-2010 remap makes the job difficult. We're definitely working uphill on the Senate in 2014, although 2016 looks as good as this year looks hard.
Further ahead, however, the future looks a lot bluer. Right now, both parties have two living ex-presidents. We have Clinton and Carter, they have Bush41 and Bush43. Neither Carter nor Bush41 is particularly active politically, although I would guess that they could be more-or-less equally effective if they wanted. Even the Republicans know that Bush43 is poison. The same is true of most of his cabinet, and they were largely retreads -- which puts most former Republican officials in the shade.
One of the negatives of Hillary's (seemingly inevitable) candidacy is that it will leave Bill in -- at best -- a less useful role than the present one. Still, look at what the future holds if Hillary is elected and her first term is marginally successful enough to produce a second term:
In 2024, the Republicans will have no senior statesmen from the executive branch who are not radioactive. The Democrats will have the Obamas, the Clintons, half a dozen Obama-administration cabinet chiefs, some coming off the Hillary administration, and a few remaining from the Bill administration.
Hillary will have appointed several Supreme-Court justices.
The Congress will have been blue long enough to enact the Dream Act, at least. Even if there is no immigration reform, the native-born, voting-age Latino population will be much larger. (And if there is no immigration reform, it will be because the Republicans have fought against it tooth-and-nail, which won't impress that population.)
Every veteran under 30 will have served his entire time alongside gay service members. That will make the Republican hostility to gay issues look quaint. Veterans don't constitute a huge block, but white veterans are a block that Republicans must hold by a large majority.
There is light at the end of the tunnel.
Keep slogging forward, and we'll reach it faster.