天不会塌下来。

The sky won't fall down.

youdao

显然，如果我们不能成功我会失望的，但天不会塌下来。

Obviously I'd be disappointed if we don't make it, but it wouldn't be the end of the world.

《柯林斯英汉双解大词典》

没有什么好怕的，天不会塌下来。

There's nothing to be afraid of. The sky won't fall down.

《新英汉大辞典》

You just can't just cast it away, and say it's no big deal. But because it is a deal.

总不能置之不理，想着反正天也不会塌下来，那你就错了。

斯坦福公开课 - 经济学课程节选