UltraViolet is not making it. Why? It seems to have all necessary ticks to make it a success: persistence of ownership of content and licenses (no crashing HDD and all content is lost), etc. etc. But (at least in my opinion) it is not trying very hard to promote itself as the best option so far. And maybe physical ownership (BD, DVD) is simple and appealing to many.Do not hesitate to react.
UV website: http://www.uvvu.com/
BluRay rocks; physical competitor very much alive and innovating: http://www.pcworld.com/article/2024919/blu-ray-looks-ahead-to-4k.html