Minecraft is a unique game. Very few games receive updates after they are released, especially commercial games. Minecraft, even after hitting 1.0, has not stopped with weekly snapshots and new releases every few months. Even though 1.0 will continue to get updates, a Minecraft 2 will likely not come. In response to someone on Twitter asking about what Minecraft 2 will have, Notch simply said, “we’re not making Minecraft 2.” There ya go, no Minecraft 2, simple as that. See Notch himself say it at the source link below.