If you could really port it to newer MC version it would be awesome.
Imho however you could even make it an external tool (like on a website) and let people import new pets via json strings or other means.
That was the original idea for the next version! JSON pets.... would be very cool. Then you could import/trade/share etc.
Unfortunately, I have no time... FT job, life, etc. Animania comes soon, then a big update to Inventory Pets... then maybe I can take a look