That is still at least a texture job (or a full remodel if the structure changes a bit like for a lot of T2 ships). Granted, it does not take whole weeks, but still needs a few days that could be spent somewhere else.
And I doubt that they have a proper T2 skin corresponding to the T2 manufacturers for these BCs. Why would they have already that ?
You should read Art sections in the CSM minutes for the last couple years. All the information on V3 is there, along with a few dev blogs and dev posts. I've been watching it closely as it goes down since I am an art addict for EVE expansions.
It's been made pretty clear right from the very beginning that when a ship is given the V3 treatment, it comes out the other side with a complete selection of skin versions. See the original Scorpion devblog as an example. Notice how it already comes with a full selection of skins? Even Ishukone and Lai Dai, Mordus, State, etc... the whole set already made. My guess is that it is done with some sort of procedural skin generation. Color values, decal templates, and a logo are selected for a variant... and that variant is applied to all the ships quickly and easily. This simplicity (though they did not specify that this is how they do it) was mentioned as one of the major reasons for going V3, because it's easier than having to hand-paint every variant manually.
Watching various data snoops who render these hidden versions outside of the game (like the chick from Caldari Prime Pony Club, and Sarmatiko) has also made it clear that this is indeed done using a system of templates, as I've seen screenshots of the templates. I've also seen ships using the correct and exact same pattern with alternate color values applied. Like a pink Navy Rokh, for example.
Some ships don't have a T2 version, or won't. Those color values are attributed to a different NPC corp instead. For example, Carthum shares the same skin as Sarum. Just a different logo. Kaalakiota shares the same skin as Home Guard. Different logo. Ishukone shares the same skin as Ishukone Watch. Different logo. See where I am going with this? This is incidentally why when the Amarr ships got the V3 treatment, many Viziam and Carthum ships carried the Ardishapur and Sarum logos by mistake. So even if the Scorpion has no need for the Ishukone T2 skin... that skin can still be used as Ishukone Watch Scorpion. On the same note... even though the Harbinger at the time had no need for a Carthum skin (Absolution), it already had the Sarum skin... which can be easily and quickly re-purposed into Carthum by using a simple logo swap.
Even if you don't believe anything of what I'm saying, as you can see by the video, the correct assets already exist, and Fozzie hasn't even decided whether or not he wants to do it yet. There is no extra several days of art work that needs to be done, so you can stop worrying that valuable time will be wasted.
I think you may be confusing a lot of things on how texturing really works, but that is a lot of info that I did not remember well or simply didn't know, since indeed I don't follow all their art panels closely.
So yes, I guess that in the same vein they already have the proper paintjobs for the new commandships (carthum/sarum, KK, etc).
On the procedural idea, I don't think so.
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That is the first texture sheet I stumbled upon, looking for an example. Every texture in 3D modeling is done like this, in more or less silly shapes depending on the software used. Even voxel painting (painting directly on the 3D model) had to be converted into texture sheets like those.
So, eve online ships probably fall into the same process as well. There are of course many ways of doing it, but eventually they have to recolor/repaint every part for it to match accordingly to the new look, for every model. They sure use decalcs or the likes, after all all of this is done on photoshop or similar software, so you just bring up the logos and images you want and start to use them as decalcs on the texture sheet at the right spot.
They do not simply press on a button and voila, procedural texture generation doing a carthum variant, a KK variant, and all. They have to change the hue, remove the old decalcs and put the new ones, change the little lights hue or where they are, add camo or else, etc.