One possibility could be to have two (main) story arcs: one where the girls' boobs stop growing at a given point, and the other where they'd grow to more absurd sizes...

(This is actually done in a certain other game but sadly, even after 15 chapters [so far?], there aren't many signs of hyper sizes...)

Alternatively, two VNs: the current one where the girls stop growing at large sizes, and then imagine a "White Russian 2" where, again, the girls grow to extreme sizes... Possibly the better option as then players would able to declare a favourite VN...

Well, this will be for Nekoma to decide... 😊