Please keep the classes.
In a dev's statement (dunno the name but it is quite a big sticky post in the fighting forum) the person in charge for the fighting system said, that the key of the current style is to personalize yourself with different fields from different classes, which would be lost with just jobs.
Personally I DO like the armoury system a lot (so please don't abandon it, SE) and the "everyone can do everything" (or at least a several things)-idea a lot and have strong objections against those games that force you into a class right from the beginning. In real life we can do several things as well, this system makes FF14 different, imo, and isn't this what people complain about so frequently? That FF14 allegedly becomes too much like other (mainstream) games?
Right now the class system may lack of some "sense" or strong distingtion because there is just one job for a class. If there are several jobs for one class though and there are stronger specialisations to differ between group and solo play then each class is a base for several branches. I wouldn't add too many new classes tbh, maybe 2-3 and make other professions new a job, or a specialist, so to say.
I like being a "simple" conjurer and change to a holy (almost all healer?) whm or back. Same with THM who is "just" an offensive mage and a blm who is a walking bomb. It's just...different to me.