Isn't there something where there is a review of your product?
I would imagine that if
WoTC had plans for a monk, and saw that you were publishing one, they would tell you not to do that.
If there _isn't_ a review process, then perhaps it would be wise for a publisher to submit planned products early on in the cycle, to prevent this sort of problem.
Also, my read of the "intent" of the
GSL (__mind reading__ here) is that they don't really want you to produce new "core" type material.
I think they want you to make new monsters with combinations of the existing kewl powers, or by applying templates, or create adventures using the existing
GSL material by reference.