NASA has announced that the next "flagship" mission will be a joint US/ESA mission to Europa and Ganymede -- a US orbiter to Europa, ESA to Europa. The US probe will have several Io flybys as it sets up for Europa orbit (personally, I find Io just as interesting as Europa).

http://www.planetary.org/blog/article/00001849/

They say the call was due to technical readiness; the science call between Europa and Titan was a tossup. I'd love to see a lander/floater/cryo-zeppelin on Titan, but Europa sounds reasonable to me. We've been churning out detailed Europa mission plans since the mid-1990s, and this plan looks fairly robust and certainly doable in the alloted time until launch. Not too smaller/faster/cheaper as with some of the late 1990s designs, or too huge and technologically demanding as with O'Keefe's nuclear-powered battlecruiser. Plus our knowledge of Titan and Enceladus is still evolving rapidly; we'll be in a much better position to know what questions we want answered and how in a few more years.

Current plan calls for dual launches in 2020, prime science missions in 2028-29.

Yep, that means TWENTY FIVE YEARS between outer planets flagship missions. Does that mean the next Saturn system flagship doesn't happen until the late 2040s? And Neptune Orbiter not until we approach the 22nd century? I'll be 60 even for the Europa mission.... I've more or less given up on living long enough to see humans on Mars but I'd at least like to see the next Titan lander!