It's always amaze me that nobody asked this question to DPC, or may be they do but he just ignore it

, That How Many In-game year he is planning.
I agree with you. I can personal see 2 year in-game. and the finale is as you said some kind of Epilogue , He is the leader by that time and ready to graduating.
The idea of having your own Maggot son , I don't think that he gonna missing out that one

.
And Yes , Winter , Spring Break, Summer, these are all thing that at least once has to happen.
The problem with the Badik, that it has so much potential the actual "universe" he created. But as a One Man Army it is truly impossible to get the full potential out of it.
Unless, he would be able to create 3000 Render and 300 animation in a month, and finish everything else in an another. and Every 2 month there is an update.