My first reaction when I saw this - probably a reaction due to previous repeated news about Voyager 1 leaving - was "But hasn't it already left, multiple times?". This is explained somewhat in GP's footnote [3]:

In early November, the team noticed a sharp decline in the number of particles, but not to zero. This means that the spacecraft still has a long way to go until scientists can declare it free from the solar system.

Due to the fact that the power of the Sun rises and decreases, the position of the heliopause is not constant. Therefore, it is impossible to say exactly when Voyager 2 will leave the Solar System.

So your interpretation is correct, Voyager 2 is approaching the boundary, but hasn't yet definitively crossed into interstellar space. The phrase 'leaves the Solar System' is misleading, depending on your interpretation of where it ends. We can probably expect a few more confused articles announcing this in the next few months until it is certain.

[3] http://earth-chronicles.com/space/voyager-2-is-even-closer-t...