My understanding is that as soon as the magnetic field shifts, Voyager will be declared to have "left the solar system".
The solar wind has died down, the cosmic rays have increased (although they are unexpectedly coming from a single direction), and the magnetic field shift will be the third and final necessary event.
And they expect it soon (could be months or years).
"To all intents, cosmic rays arrive evenly from all directions in the sky, but this does not necessarily mean their sources are evenly spread around us. More likely, they are constantly deflected and scattered by magnetic fields in the galaxy, until any trace of their original motion is lost."[0]
A crude hypothesis would be that there's some sort of magnetic field that is directing them from a single location. Since we've never been this far before, its a pretty huge guess...
The solar wind has died down, the cosmic rays have increased (although they are unexpectedly coming from a single direction), and the magnetic field shift will be the third and final necessary event.
And they expect it soon (could be months or years).