It really doesn't matter where the ship goes now, or when it gets there. Sagan has his monument, and I am happy his wife got to work on the design.
Cosmologists haven't tackled it yet, apparently. The scope isn't cosmic, just something in our backyard.
Still, as others have mentioned, there appears to be something going on that our wonderful physics hasn't accounted for. Who knows, it might be important, although it seems like a small effect, an impact to the gravity constant way down in the less significant digits.