I believe capes work on the same system as skins. This means he's have to incorporate capes into a adjacent system. He once said we could make our own capes in the future, but withdrew it as a secret soon after. But considering we could use that to replicate special capes, he might not let us do that at all. I would like a Beta Tester optional cape, even if it isn't of great significance, for the sake of it.