The scale dilemma
As indicated, NoSQL is perceived as more scalable than SQL databases like MySQL. Most people would rather work with a scalable SQL database and not take the risk of using NoSQL, unless it is the only way to go (which is possible when very large scales are needed, Facebook / Twitter kind). 99% of the market would find a scalable SQL solution more than sufficient for their needs.
Few solutions are in the market today for scalable MySQL. For example, Xeround is one of the leading Scalable Cloud Database solutions.