Yeah but it's even more liekely to change than other stuff. They regularly look at statistics, and if I remember well, space elves (and more generally humanoid portraits) were the most used of all portraits. Releasing more "alien" alien portraits without including something people are asking for (either more humanoids, or one of the popular things like robotic variations) would be a bad move.
Now, I would love if they focused on bringing more variety to existing portraits, either on the basic level, or when you have subspecies or cyborgs. It would also be really cool if different pops from different planets developped different visual cultures (wearing different kinds of things depending on the climate of the planet they live on, for example).
I agree that they should make more rubber foreheads and that their plans may change and I hope they do. The point of my quotation of Wiz was that that was the last time I saw a dev talk at all about future portrait plans, and that he did infer that they would have a modus operandi going forward. Other posters had previously offered skepticism that there would be more portraits.