Depending at what generation your Digimon is at is when he'll degenerate or fade away. Also how you take care of your Digimon. Champions usually die or digivolve at the age of 12-14. If you fill Ultimate requirements they will digivolve, if you don't, Your Digimon Will most likely die. Although if your Digimon lives to the age of 15 it will digivolve into Vademon. Having high happiness and low discipline increases life span, while low happiness and high disc decreases it. Also if your digimon poops on the ground life span decreases by a little. You could give digimon chain melons or digiseabasses to make them live longer. You obtain chain melons by beating the last boss and talking to Jijimon. DigiSeaBasses you can fish. Ultimates usually die at the age of 17-21. Fresh/In-training/Rookies will digivolve 99% of the time. But if they dont they die at the age of 9-12