Erik Todd Dellums, a voice actor who voices Three Dog, the DJ of Galaxy News Radio in Fallout 3, has recently tweeted at the possibility that more could be on the way.
Erik has later confirmed that he been given permission to release that tease. NMA has already supposed that this could be the start of a viral campaign.
According to rumors that has been circulating back in August, Bethesda Softworks was doing an initial research for Fallout 4 in Boston area.