[Dragon Ball] What if... an incursion on Earth's Dragon Ball?

Let's assume that after the defeat of Majin Buu (and before the appearance of Beerus), another Earth appears right in front of the Dragon Ball Earth, leaving only eight hours before the universes are destroyed.

How do you think the crisis would be resolved? Who would be in favor of destroying the other Earth—sacrificing millions in the process—in order to save their own planet? Would the Dragon Balls be effective in preventing the Incursion?