One report would like to say so:
Blogs were once the outlet of choice for people who wanted to express themselves online. But with the rise of sites like Facebook and Twitter, they are losing their allure for many people — particularly the younger generation.
Sure, the numbers might be there, especially for that younger generation, but that generation will grow up and realize that they have to put on their big boy pants and actually write something longer than a sentence (or fragment) to communicate effectively: