I'm in agreement, specifically with the breakup when one cat turns 121 days.
Or, block the kitty from being able to partner if there is no way it can produce a kitten within the time it has left. The system should be able to calculate when there is no possible way the cat can produce another breeding, even with milk or love potions.
The permapet discount would be a phenomenal incentive. Members have been begging for a price cut for a long time. It would increase sales for people who don't want to breed and just want a pet, as well.
I have been breeding for almost 2 years and I have cut waaaay back to only 6 or 8 breeding pairs max due to economic reasons. I know this isn't anywhere comparable to other breeders, but it's all my budget can handle at the moment. I keep telling myself when I finally get this specific kitten I'm breeding for, I'm done.... It looks like it will never happen, though! lol so for now I'm still in it