Turing completeness is a horrible idea for scripting in a cryptocurrency. Just look at the past couple of decades of vulnerabilities in java, javascript, flash, etc, etc. Turing complete money will drain your wallet on it's own.
The only thing I can see stopping it is another cryptocurrency which accomplishes everything that Bitcoin does and more, only with a codebase so different that Bitcoin can not adopt these added desirable features.
May I ask how important you feel Turing completeness is in the scripting language?
I'm sorry, I do not have the technical knowledge to answer this question. Give me a few days and I may be able to give you an answer.