There will be large breasted females in future versions. Self collision between breasts is needed for this, but that is possible.

Well, that sounds somehow... mouth-watering.
But I hope that these breasts don't get as enormous as those of Lolo Ferrari or Diva Mizuki. If you don't want to break the first-person-immersion, having a woman with atomic tits surely breaks the virtual experience into bits and pieces and turns it into a cartoon, in my honest opinion.

On the other side, have you thought about lactation? I found the mucus-demo-vid quite impressive, and I think it's only natural to combine bigger breasts with lactation. But only in situations/stories where it makes sense. I don't think that Samantha, Latisha, Jenna and Tiffany should be able to lactate, because they haven't been pregnant (as far as we know). But the suggested MILF-stories I have read so far could make use of lactation. Of course, you shouldn't exaggerate, I mean, having your MILF squirting massive streams of breast milk all over the place is nonsense, but leaking runlets on arousal or orgasm over breasts and stomach, or squirting a little when massaging her breasts? Yummy!

Would you like some MILF with your coffee?

EDIT: I would vote against fluids injected into nipples to enlarge breasts, because this is impossible. If there was something like this in reality, there would be no need for breast implants.