They will likely be the last evidence that the human race ever existed.
In 2-3 billion years the sun will leave the main sequence steady state it has been in. This will end in it turning into a red giant, and engulfing earth and destroying all record we existed.
Meanwhile, the journey of Voyager 1 and 2 will have only just begun. They will continue moving through the expanding universe for at least 3,000,000 Billion years.