Some new official info from ubi forums

[The Kraken]

Originally Posted by kendo65

Surely the skinners will still be able to weather their skins in the same way as before. All that we'll have to do is to turn the COD weathering off (ie set the slider to zero). Skinners could even release a 'clean' skin for use with the COD weathering and a pre-weathered skin.

The weathering will also have a specular map (where the underlying metal is exposed), which may not be available to "normal" skinning. So this approach wouldn't provide the same options and quality as the built-in weathering system.