Thank you for the comments. Yes, I agree that it may take a long journey to obtain legal enforcement on the smart contracts and it would not happen in at least this decade.
However, in the longer term, I believe that we will eventually see the blockchain technology with smart contracts (or other forms of applications) everywhere sooner or later this decade.
Big companies are currently building up own private blockchains, but sidechain projects will provide platforms for many ordinary programmers with good ideas to develop blockchain-based solutions and I am expecting that some of them would achieve a great success (like Facebook these days).
In this situations, I am wondering if the success of applications based on the sidechain will drive the price of Bitcoin. I am not clear about the relationship between the huge demand on sidechain currencies and the price of Bitcoin. I understand no one can provide clear quantitative analysis on this topic. But, I am seeking rough (but rational) explanation or prediction on this topic.