As many know by now Dragon Ball Super is about to start a brand new arc featuring Future Trunks and a Evil Goku on June 12th on the series 47th episode. I also want to give everyone a heads up before they continue to read that this is mostly speculation and may have some spoilers, so enjoy.
My theory is that this Trunks is from the current timeline and not the Future Trunks from the Android and Cell Saga. That timeline has been changed, so it is unlikely that Trunks will return. Instead, it is more likely that Beerus accidentally wished back Universe 6 Goku when he wished the Universe 6 Earth, so Champa could enjoy Earth Food. That being said I believe that this trailer hints at some of my points.
My understanding of the Japanese language is still very basic, but the trailer basically says:My name is Trunks, I’m from the future. Mother please, wait for me. SOS from the future! Next reveal, New Black Enemy appears. As far as the image above it says: In the next development of Dragon Ball Super Future Trunks comes back. After the Universe 6 competition Trunks will do something. Why is Future Trunks back after taking out Cell and getting peace; is there a new enemy? June 12 is when a new arc starts.
If anyone has a better translation, then please leave a comment so this can be corrected, but for now this will do.