This hypothetical has several issues, the first being that the Earth's Dragon Balls are incapable of such a feat. The Namekian Dragon Balls were capable of restoring the planet Earth and its people in the Majin Buu Saga, but I find it unlikely and out of character for Goku and Vegeta to use the Namekians' wish orbs for something so trivial. Not to mention the harm they could cause the galaxy; remember, the Saiyans were a warlike race who reveled in destruction even before Freeza's takeover.
Secondly, neither Goku nor Vegeta have expressed any desire to restore their race in canon materials. Goku has zero attachment to his Saiyan heritage, meanwhile even the prideful Vegeta finds the idea of a reborn Saiyan race intolerable. In Chapter 204, Nappa suggests that he and Vegeta interbreed with Earthlings to create a new Saiyan empire, an idea which Vegeta criticizes because the offspring would be more powerful than them. Vegeta detests being outclassed, even hypothetically. Apart from his tears shed on Namek, he never displays sentimentality towards his people.
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Fate: An event that must happen no matter what. Nothing will happen without it. Many things can be imagined from what is seen.
