It seems like the primary focus of JUNO is to get a better idea of how Jupiter works. The Science Objectives listed on Wikipedia don't seem to include anything about Jupiter's moons, other than a desire to not impact them. Will JUNO contribute in any way to the understanding of Jupiter's moons?
According to the Mission Juno mission page, the only scientific data that will be done will be on Jupiter itself, there is no mention whatsoever about any studies that would be performed on the moons. In fact, Juno will be spending a lot of its time in very close proximity to the planet - well within the orbits of all known satellites.