Eh... If you think about it, video games are kinda new. I'll bet it's going to become a Space Invaders or PacMan thing (My best examples ) and it's going to become not as popular but people will be itching to play more of it. In the future like twenty years from now there will very unlikely be an MC II. But someone, like DiamondQuiver mentioned, will want to take over. And if they're metaphorical descendants of Jeb and Notch, well, forget about Minecraft dying. It's just gonna get better!