I was watching Seabiscuit last night, and one of the characters said "The sky's the limit!" in reference to his future. The movie primarily takes place in the 1930's, and I was struck by the thought that, in that era, the sky really was the limit. Yes, people could dream about being on the moon, and space flight obviously was as potential then as it is possible now... but in real terms, the sky was the limit, we couldn't go higher.
That got me wondering if people still say "The sky's the limit" when they are talking about things that have no boundaries or limits. I think they do. Heck, I may even say it myself. If so, we are limiting ourselves.
I say it's time do away with "The sky's the limit". It's time has passed. We should, however, replace it with something similar, just so people will still have a limit to strive towards.
How about: "The Galaxy m104's the limit!"