There is one feature noticably missing from the new Minecraft launcher - an offline mode option. Many have speculated that Minecraft is moving to an 'always online' mode similar to Electronic Art's SimCity 5. However, as noted in bold red words, the launcher is still in development and has not yet been adapted for offline use. Nathan Adams, one of the main developers of Minecraft said, "he launcher is still in a testing phase, and the "Play Offline" option simply hasn't been added to the menu yet. It is coming in future launcher updates, and will remain a core feature of the launcher." So there you have it, offline mode is most certainly not going away anytime soon.Source: Minecraft Forums