Didn't they say that about cars back in the 1900's?
It's taken a while, but for cars it's def happening now. You just have to see how much the Prius has sold worldwide. And how every manufacturer is scrambling to get electric or hybrid cars out on the market.
Aviation might take a bit longer, but I'm personally 100% certain it will happen in my lifetime.
And Tazzz, that seems like yet another version of the elusive perpetuum mobile. It hasn't worked in the last 500 years and will never work as long as Newton is in control.