The texture layout for upgraded content is the same, yeah. However the car bodies (and open wheel helmets) need new alpha layers to get the correct level of reflectivity in 2013. Skins copied across from 2012 will "work" but will be too shiny across the board.
As well as the normal template downloads which will already have the new alphas built in we'll have a separate "conversion" pack up with just the new alphas in. Probably in the form of TGAs you can paste old skins on top of then save out as fresh DDS files. The 2013 StockV8 templates have new contingency sponsor layers, though they can be copied out easily. Or old skin layers can be put into the updated templates, either way.
A little headache perhaps but quite easy to do, particularly compared to having to recreate all your skins. I suppose it'll also allow for a clear distinction between 2012 and 2013 skins, which isn't necessarily a bad thing
