Digimon Adventure: Last Evolution Kizuna is a celebration of the Digimon franchise's 20th Anniversary, but at the same time it was also a reflection of just how long 20 years truly is as the original chosen children learned their Digimon partnerships have an unexpected ending point. In explaining this, the film also explained why the DigiDestined didn't know there would be such a hard cutting off point for their Digimon friendships. Because as the film explains how friends begin to drift apart after spending so much time together, it's one of those things that remains unspoken.
Digimon Adventure: Last Evolution Kizuna sees Tai and Matt coming to grips with a new hard time limit placed on their partnerships with Agumon and Gabumon, and when they realize they are in trouble, there's a surprising return that helps to truly cement why Tai and the others didn't know there would be such a terrible goodbye someday.
As explained to Tai and the others, the DigiDestined all have a set time limit on their partnerships as Digimon choose their partners according to their potential. Children have boundless potential in their lives, and are thus chosen by their Digimon partners because that potential turns into energy that helps them evolve and grow. And when that potential disappears, so does the Digimon.
Although the DigiDestined had said goodbye to their partners in the first two seasons (before the Digimon Adventure tri films seemed to imply that these adventures could go on forever), Gennai surprisingly makes a grand return to the franchise to explain to Tai why the kids never were told about their partner Digimon's true fates going in. It's just something you don't say.
Gennai reveals that it's not a subject that is brought up lightly, and it's like telling someone when they are going to die. This implies that Gennai always knew that the Digimon partners would fade away from existence someday, and has been holding this back from the children who were already facing some serious challenges.
But in the film, Tai and the others were finally mature and strong enough to deal with this news and were strong enough to truly accept what the "end" truly means this time around. But what do you think? Did you expect the Digimon franchise to broach such a major subject like death in Last Evolution Kizuna? Let us know your thoughts in the comments or you can even reach out to me directly about all things animated and other cool stuff @Valdezology on Twitter!