It has been a whirlwind couple of days for gamers, as Bethesda Softworks teased Fallout 4, and then announced it the next day. The actual launch date of the game hasn't been announced, but it seems likely Fallout 4 will be available before the end of 2015.
The official Bethesda online store originally had the title listed as "TBA 2015," which has now been changed to just "TBA." However, GameStop and Amazon both have the title listed for 12/31/2015, an unlikely date that is more of a placeholder for a late 2015 launch.
Gamers do know Fallout 4 will be available for the PC, Microsoft Xbox One, and Sony PlayStation 4. We'll just have to wait and see what Bethesda has up its sleeve for E3 later this month - where we'll hopefully learn more about Fallout 4.