Freeza would know that Saiyans can survive in space, so he wouldn't have bothered trying to blow up Namek. Not
being in haste to leave after the fight, there is a chance that Goku does not spot the Ginyu spaceships and just
waits to be transported to Earth through some dragon ball wish. If Freeza still survives Goku's blast and Goku spots
his body, I guess he gives him one more chance and takes him to Earth with him to heal him. Cold does not attack
Earth, since he never discovers his son's body.
Without Cold's attack, Trunks sticks to his original plan and meets only Goku. Goku does not remember where
Androids will strike (In canon, it was Piccolo who remembered.), so Nineteen/Twenty cause some damages before
Z fighters see them in the tv news. As for Freeza, I guess he has trained for the Androids as well during the 3 year
old period and become a Z fighter. From there on, it depends on how you view Freeza's gains.
1. Freeza has DBS gains.
Even though he's SSJ Blue level, after spending some months/years with Z fighters, and being curious to see Androids
on top of that, he has cooled off a notch, so he doesn't just go and kill everybody. He solos all future threats (Androids,
Cell, Dabura) and makes himself comfortable on Earth. If Beerus wakes up anyway and Goku/Vegeta become Whisses
students, U6 tournament is won even more easily, Zamasu is defeated even more easily (thanks to Freeza's help) and
TOP saga goes as we know it.
2. Freeza has reasonable gains.
I don't think much changes at Androids/Cell/Buu sagas. Freeza is reduced to a sidekick, like Piccolo and humans.
