Note that this is the quote in context:
There will be four disciplines, each with a number of classes, and a variety of skills for each class. The developers are still unsure whether players will be able to master every class, of if they will impose a "see-saw" effect, similar to crafting in Final Fantasy XI.
Note that the only "see-saw" effect in FFXI's crafting system is that you can't master all crafts; just one, but you can develop the others up to 60. Working on Goldsmithing does not ruin your already high Cooking skill, but if you want to master Goldsmithing and already have 100 in Cooking, in this case you'd be forced to relinquish your Cooking levels. Alternatively, you can distribute the 40 post-60 skill levels as you wish, thereby never mastering more than one craft (with the exception of Fishing). Deleveling is by choice, not the natural progression of every-day crafting.
Many people have jumped on the idea that by "see-saw" it means that by developing one skill you're simultaneously eroding another; they're envisioning a literal see-saw where as one side elevates upwards, the other declines to the ground in a repeating cycle. The information points more in favor of FFXI's crafting "see-saw," where one must choose what to master, but you're free to level up the other jobs to a certain point before you have to choose what to specialize in, the "see-saw" only coming into effect when you choose to take up mastery in something new. While this does lend to the idea that to have multiple mastered jobs you'd need a new character, it might not be that bad, especially if switching what skills you're currently a "master" at is as simple as a trip to the Mog House (or something of that nature).
The developers have repeatedly stated that they want a system wherein people are able to switch jobs and still maintain their "levels" in that job, similar to FFXI's job system. It wouldn't make sense to implement a system that causes the player to lose a large amount of development when they change their mind later on. Given the emphasis they've put on more casual play and more player freedom, I'd expect them to come up with something that lets you simply move those skills around at a certain point, rather than lose that effort completely.