Doesn't it eventually crash into a star and get turned back into atoms?
In all likelihood I suspect such to be the case, eventually. While the odds of such a tiny craft's path crossing that of a star given the vast emptiness of space is almost zero, unfortunately all that's needed is for Voyager to get caught in a star's gravity field, an exponentially larger area, and then gradually get sucked in.
That said, as already noted by others, it'll be 40,000 years before Voyager even approaches our closest neighbor at a distance of well over a light year. Voyager will be floating through space for tens of millions, if not hundreds or even billions, of years. It will outlive humanity by a crazy amount - it will possibly, probably even, outlive our sun's remaining life.
Plus, figure we have four shots of survival - two Pioneers and two Voyagers. Assuming New Horizons survives its encounter with Pluto, which isn't definitive given how far away it is (It could,
could meet up with some tiny satellite of Pluto's, a captured Kuiper object too tiny for our scopes to have a possibility of resolving.) Let's say it does, and then we have five emissaries to interstellar waters.
While we can't say for sure when or if any of them will meet an end considering the insane scale of time that needs to be factored in, all of them will be drifting for at the very, very, very least millions upon millions of years. Multiply our chances by five different craft, and who knows, one of them might just be lurking around the darkness when the last stars blink out and die.
The only thing I don't know, and imagine there isn't a ready answer for via Google, would be the galactic notion... These craft obviously all will escape our solar system, but none will escape the galaxy. I don't know if, as a consequence of that, over billions or even trillions of years whether or not the black hole at the center of the Milky Way will exert just the tiniest of pulls to eventually suck them in should any of them otherwise survive after quadrillions of years.
Regardless though, it's just such a magnificent feat and the pinnacle of our species entire existence. We've got things that were made by human hands on the planet of our birth that will last for an inconceivable amount of time. No matter what happens to us, or our entire planet, there will be five tiny reminders drifting in darkness to let the universe know we were here and just how much we accomplished as a people. Amazing.