Как по Английски будет пирог в небе

phrase

Used to describe or refer to something that is pleasant to contemplate but is very unlikely to be realized.

Примеры использования:

Don't throw away a decent offer in pursuit of pie in the sky

idiom

Something good that is unlikely to happen

Примеры использования:

I wanted to be a major league baseball player, but i knew it was probably pie in the sky.