No matter if you like or not, video games franchise can't go on forever. Just like Kingdom Hearts. When will the franchise end?

I hope that one day, I can talk to my grandchildren about Kingdom Hearts and how I was there when it all started.

KH will end when a successful franchise usually ends -when they've milked it dry

Kingdom Hearts will undoubtedly last for a very long time, I'd say at least for two or three more decades!  But then again, it could last even longer!  As long as Disney keeps releasing Animated films, Nomura and the gang will keep on drawing more worlds from said films!  And as long as Nomura keeps on inventing new and creative combat mechanics and engaging stories, I see the series standing the test of time for many years to come!  Oh, I'll be sure to introduce my future children to the KH series from early on, so they can enjoy the wondrous world of this series! :')