Just to clarify, Neutrinos are not a theory; they have been proven to exist. Aproximately seven are detected each day at the Sudan Laboratory. It is still unknown how much neutrinos account for dark matter but they are still classified as dark matter.
And I don't think there is going to be a picture of the dark matter. A picture requires light to be emitted from the dark matter (does not happen) or reflected off of it (theoretically does not happen either). Hubble is not that good

On the NASA page, it states that it will show a mass distribution, which is what Edwin Hubble had theorized and calculated from measurements of the Milky Way. The distribution will probably show visible mass (stars) that are reacting to the mass of the dark matter. Still, that is pretty good evidence. There was mention of two objects, (galaxies or clusters) so the imaging may also involve gravitational lensing. The mass of the objects can be calculated from the light intensity generated and then compared to the mass calculated by the gravitational lensing. The difference of the two will show the mass of the dark matter. It will be interesting what NASA has to say.