Gonna go ahead and say that what you're suggesting will never happen. You can quote me on it, I don't care. The technology required to let you even purchase the gear would have to be rewritten. I'm more interested in whether or not I can transmog my staff into a polearm as a priest. You're supposed to be able to equip the item in order to transmog it, but now staves and polearms are interchangeable, and that interaction hasn't been confirmed yet.