From what I am aware, there is nothing planned for that.
Although, from a technical aspect, if something like breasts, balls, etc. pregnancies were to be implemented, they would require an expansion to the current pregnancy system or be treated differently, possibly as timed status effects. In either case, it will be a technical hurdle as breasts/balls/etc. can be changed, very much like how vaginas can be changed, added or removed. It would require checks before changing to avoid issues with starting and ending conditions. I would assume most checks for that are already covered in some items and events, but some may not have it that may need to be adjusted to account for the new feature.
So with that, it has to be noted that there has to a substantial amount of content to even justify the use of alternative pregnancies.
My suggestion: make it a parasite-related project. Have the parasite "lay eggs" into the affected spots (breasts or balls). The affected spots will temporarily expand via the status effect left behind. If the affected parts are ever fertilized, either by another parasite or another semen load source, there is a chance the eggs may grow and produce more of the same parasite to birth/lay when the status is removed. If the eggs are not fertilized, they will be absorbed into the body part being affected, possibly expanding it by a small bit, when the status effect is removed. If, by some reason, the affected body part was removed, the status effect can be forced removed during the status effect check, with or without notice. If, instead of being a status effect, this was handled with the pregnancy system, it may more difficult to technically implement but will retain traits like pregnancy speed, etc. and if it is integrated and there is written content for it, the parasite can also impregnate the ass and vagina as well. Things to consider are the affected body parts' (and their orifices') type, size and location. It may be possible to write a one-size-fits-all, but that would lack the flavor for uniquely shaped body parts (such as inverted nipples, dicknipples, lipples, tentacle nipples, uniball, double cock heads, ovipositors, etc.)--whatever is relevant.
