Well we got our first look at the newest upcoming villain. Thank god, he's not literally a "black" Goku or "shadow" Goku, but his name figuratively being "evil" Goku.
Though we still don't know if this guy is literally an alternate version of Goku, or merely a separate character who looks like Goku. All we do know is he is powerful enough for the Omni-King (who's capable of one-shotting the multiverse) to get involved. Which would mean Black Goku sure is freakishly powerful.
So why did they go about making an evil Goku to begin with? Well, doesn't it make sense that the greatest hero in existence can also be the greatest villain? This may mean that Black Goku has all of the potential of regular Goku, possibly having tapped into earlier.
Now I've heard theories that Black Goku is from Future Trunks' Universe 6, and that he was the protector who somehow turned evil on his own. I'm skeptical of this, as we don't find mirror characters running around the 2 universes (they're more like galaxies, but larger). Also, it's repeatedly emphasized Goku is basically the embodiment of purity and goodness, and would never turn to evil on his own.
If Black Goku really is the same guy as our Goku, then he would have turned evil through external means: mind control, magical corruption, or any empty shell being used by someone else.
I've also noticed in the image Black Goku is wearing earrings that looks suspiciously similar to Potara. Could Black Goku be the result of Goku fusing with a being who's pure evil? That could explain his massive power gain that requires the Omni-King's attention. It might also cover for why Goku is still alive in the future, since as Vegito has shown, one of the fusees is allowed to be dead.
Also, is Future Trunks coming back to ask for help in dealing with Black Goku, or is he trying to create another alternate non-apocalyptic timeline? Also, why did he come back to this late in the past, and not say, during the Buu saga?
Most sources seem to indicate Trunks narrowly escaped with his life and needs aid. It also sounds like to me, this era of Super has some significance regarding Black Goku, and the present Z-fighters will face him in their time. But is it going to be an earlier version of Black Goku that already exists, or can the Future Black Goku somehow travel through time? I'd like to think it's the latter, since our Goku is still alive and good, and you'd think the Gods would have noticed a being powerful enough to threaten the multiverse.
So what do you think? Do you agree with me, or have your own theories? Let me know in the comments.