有朝一日

有朝一日:

Literally means:

some day

Actually means:

surely there will be a day (when something comes true)

It refers to one day in the future. It indicates that the thing the speaker has eagerly anticipated may happen one day or that the speaker can make that happen eventually.

It also implies that a major event may happen one day in the future.

将来有那么一天。常表明说话人期待的事情能在将来的某一天发生或完成。

也预示将来的某一天会发生某件比较重大的事情。