It won't wear out, but it'll shine. If you look at an old laptop (over a year old, not weeks), and that person has used it a lot, it'll tend to have shiny trackpads or darkened palmrests that become difficult to clean if you don't do so regularly. However, they can be cleaned, which proves that they're not actually being "worn out".
The "shine" people are complaining about is caused by both Apple's use of smooth textured keys, plus by oil from your fingers. Previous MBPs had keyboards with keys that were not completely smooth. There was a subtle texture to it, and that's why they didn't get all shiny.
It's not due to manufacturing defect, so don't worry. Just clean it with something that can cut through oil. Or sometimes, just use a tissue and wipe up the keys and palmrests. All the MacBooks have had this problem (black and white), and the keys on the new unibody MB and MBP are even smoother than the plastic MacBook's.