Some things can't be changed now, so there's no point in distressing about them. Some other things can be fixed or added with a deprecation. So my suggestion is to write down a very long list of the things you don't like, remove the ones you believe are impossible changes, and open a separate RFC for each of them for the Rust 2018 edition (or where possible even for Rust 2015). And then be humble when people tell you some practical problems. Most ideas will be closed or shot down, but if even very few see the light in Rust 2018 you will have a positive and multiplicative impact on future Rust users 
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