What some one - I think kibwen - has brought up is that early adopters can benefit in the sense that the language design is still in flux. So these early adopters can uncover weaknesses in the design, before they get to the stage where they have to consider backwards compatibility.

So although early adopters might not get any useful software out of learning Rust at this stage, they might indirectly improve their future Rust code by having a small influence on the direction of the language.