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.
As that 'taken a while' has been about about 100 years, I'll wager a fiver on that last sentence
