So, classes are still very valid post Job system.
From what I have read, it seems to me that the way they have implemented the job system still leaves plenty of room later on for the base classes.
They mentioned that Class specific gear will be introduced later.
Also, when you select a Job, you limit your other abilities to one class, whereas people who stick with a class, can select more abilities from other classes.
Perhaps this is old news and I deserve a "Welcome to last month".. But I think this is pretty cool! I was a little worried that the Job system would make the base classes obsolete, but I can definitely see the benefits of sticking to a class over a job if that is what you prefer.