YOU SAID:
what would happen if the world ended today
INTO JAPANESE
世界が今日終わったら何が起こるだろう
BACK INTO ENGLISH
What will happen if the world is over today
INTO JAPANESE
世界が今日終わったらどうなるでしょう
BACK INTO ENGLISH
What will happen if the world is over today
That didn't even make that much sense in English.