The new trailer for Dragon Ball Super: Super Hero features a fight scene that hints at a return to a place we haven't seen in years: Namek. We can make this guess based on the emphasis for Piccolo having a physical house, as well as the color of the grass -- blue -- that Goku lands on during the fight scene. Blue grass has only ever seen on Namek and New Namek, the home of Piccolo's race. This could be hinting at a reunion with the Namekian people, who were killed before Goku defeated Moro. Thankfully, they were revived after the dastardly villain's downfall.
We've also learned that Piccolo finally got his own home, little mailbox included. It shows how views the Earth as his home and that he plans on living there for the rest of his life. What's surprising is how long it took for the creators to give Piccolo his own home-sweet-home. This could be a setup for the Namekian warrior to question where he truly belongs if a return to Namek is actually in store. After all, he didn't even know he was an alien until Vegeta and Nappa came to Earth and called him a Namekian.
The inclusion of fellow Namekian Dende in the character designs seems to support this return to the Namek -- or rather, New Namek since Frieza destroyed the last one. While the rest of his people moved to New Namek after about a year on Earth, Piccolo stayed behind and took on the role of Guardian of Earth in Kami's stead. Dende was later brought to Earth by Goku to take Kami's place, but Piccolo stayed because he saw the Namekians' peaceful lifestyle as dull and boring. He preferred to stay on Earth to protect and train Gohan, with whom he formed a lifelong friendship. With Goku's son now all grown up, Piccolo has been shown to be close with Pan, Gohan's daughter. He trains with her and even thinks he does a better job of watching her than Chi-Chi does. How their relationship will play into the return to Namek is unknown, but it could be very important.
Inevitably, the Dragon Ball Super: Super Hero trailer's reveal also means the Namekians will once again be in danger. There is a combat caste within their society, but they may not be able to handle the Red Ribbon Army alone. Once the fight moves to their planet, they are almost certain to lose a few unfortunate citizens. What role Piccolo will play in their protection and how it will affect his place on Earth may be a major plot point for the movie. Namek is the origin of the Earth and the Dragon Balls. This could possibly mean the Red Ribbon Army are after Planet Namek's Dragon Balls as well as Earth's.