It's probably best to expect the champions with simple, single- or double-hue color schemes (the simplest ones) to be chosen for Chroma packs first. Would also bet on more popular ones to get them sooner.
THis is if they even see interst lol. THis could all just go down the crapper if people don;t really care fro it. I would honestly rather have alternate ways to unlock them ((which the said are probalby going to be doing or that it is possible.))
Also... starting with Luci for the Champ was a smart idea, gives a good idea of what they would change and how much etc... I like it and certainly hope it does catch on.
Even if only 10% of people buy it, they still make a decent profit and the interest is there for those who want it. They don't really take much effort to make like a skin, either