Dragon Ball Super
While Future Dende was never shown in Dragon Ball Super, Goku Black and Future Zamasu clearly said they destroy all of the Dragon Balls and they destroyed all of the mortals except for Earth. It is hinted that Dende and the rest of New Namek was destroyed by Goku Black. His soul was destroyed when Future Zeno erased the future timeline to kill Infinite Zamasu once and for all.
Shin Budokai - Another Road
Future Dende is on New Namek, where the Z Fighters appear to reunite the Namekian Dragon Balls before Future Babidi and his allies Future Broly and Future Cooler. The Z Fighters reunite the Dragon Balls before Future Babidi's allies, but when Future Dende is about to summon Porunga, Future Babidi appears with Future Broly and Future Cooler. The Z Fighters fight Future Babidi's allies while Dende invokes Porunga and makes the three wishes: the first is to revive those slain on New Namek, the second is to eliminate the Big Gete Star, and the third is to bring back the destroyed villages. Before the third wish is made, Future Babidi tries to attack Future Dende. Future Dende cries for help, and Porunga takes this for a wish: an unknown spirit then appears and stops Future Babidi, so Future Babidi leaves New Namek. After that, Future Dende goes to Earth, where he becomes the new Guardian.