A year is a long time for that.
Not when you consider all the other work they've been doing.
That being said, in my experience from other MMOs, a lot of the time (but not all), when content is released they are well into development of the next content upgrade. However, as someone else already said, EA/BioWare was probably waiting to see the results of F2P before committing resources into content (that might never be released).
Lastly, when you consider the SWTOR story arcs are more detailed than most other MMOs (voice acting, conversations, etc), if they keep that quality level, I do not expect new chapters for at least another year.