What does a new patch mean? A sudden increase in new gear that must be gemmed and enchanted.
This in mind, go stock up on gems, saronite ore, dust, and essences (Enchanting materials may or may not be profitable due to already inflated prices, but I may be wrong). A few days in after the patch hits, prices will increase a LOT.
Increased demand in raw materials after content patches and arena seasons has been demonstrated many times in BC. There is no reason that it will be any different for WOTLK.