Goku and vegeta will train for a short time and when the time machine is fixed will travel to future to face Black. Vegeta will insist he face Black first. I believe Black's ability is to copy another person's power and make it perfect. Thus anyone he fights he will soon get stronger than his opponent's current level of power. He will tempt vegeta to use his full power when realized he's been facing goku and vegeta at a fraction of their strength by using future Bulma's death as a kickstart. Vegeta will get enraged and use his full power which Black will copy and get stronger on top of it. He will overwhelm goku, vegeta, and trunks. Then go to present to destroy everything but not before goku steals the ring of time. Black will go against gohan who gains a little bit of his mystic power back by going into a rage from videl being hurt. He will land a few blows against Black who can't stop his ability to copy gohan's level who's weaker than goku or vegeta. Gohan either dies or is at near death. When goku appears. Witnessing the destruction goku goes into a rage and transforms into super saiyan white. Black will be a little weaker but super saiyan white makes the person grow far more stronger than his opponent. goku will win and after black will reveal his true identity/ form. whether they finish the fight in the present or future I don't know. but AKira Toriyama was big on contrast. And Black goku vs. Super Saiyan white Goku is too good to pass up. I expect a very good final fight and hopefully some loss and drama to boot in this arc...... (what do you thinK? and what's your predictions?????)