What is halting the evolution of a single service oriented language?
Technology takes time to evolve. There is huge inertia with existing code bases and applications, organization maturity and process, developers skills, etc. There is also a grave need to address the problem of the present, not of the future. But more than anything, software is not perceived or practiced as an engineering discipline.
There is a multidimensional industry-wide crisis that drives the cost and effort of ownership of software through the roof and unless we do something about it, this industry will eventually find it noneconomical to develop software in the West. It's not that you cannot do good software -- clearly there are plenty of fine examples of both high quality products and well-managed companies that are within the adequate limits of budget, time to market and quality -- but that tends to be the exception rather than the rule.
Unlike almost any other engineering disciplines there is no regulated licensing process or industry standard. There is no requirement for studying software engineering in order to program for a living. Hardly any university in the world is teaching software engineering as opposed to computer sciences, and there is at least as wide a gap between the two as between teaching physics and teaching mechanical engineering.
On top of all this, there is a huge skill gap between what most developers should know and what they actually do know, and that translates to a gap between what most developers should be able to do and what they actually produce. Most organizations lack development process maturity for producing good software, and most projects resemble a lucky strike or a death march, with little repeatability. I am not even talking about good design, architecture or security. All of these reasons, despite the fact that software development is a highly engineering-oriented activity and that we have both the process and the design methodology to do it right. This is really what is holding back the industry.