Okay it seems funny to say that blogging is getting "old" but sometimes teachers and students are looking for alternatives. Here is a listing from HP Teacher Exchange of some other sites which offer alternatives to blogging if you are looking for a change of pace.
The first site mentioned is Tumblr. Tumblr allows more text than Twitter but not as much as a blog so this might be perfect for reluctant writers. Now I must admit when I tried to look at it here at school, I was blocked and the reason was "pornography" so you might want to check it out before you turn your classes loose on it.
Storify is another suggestion. My sister sent me a great story written by my nephew on this site. It combines the best of writing with social media allowing students to put together a great story.
Anything that gets students to do more writing is a good thing. If you're feeling brave and are ready to move your students out from blogging, give one of these sites a try.