All the signs are pointing to E3 for Fallout 4’s announcement and we won’t be surprised if it happens. This is because Bethesda has also teased on Fallout 4’s possible confirmation at E3.
However, there are some things that Bethesda should avoid saying at the event or they will see their headquarters turning to rubble. Based on the ‘worst case scenario’ discussion, it is clear that Fallout fans don’t want Fallout 4 to be an Xbox 360 exclusive. Heck, it will be much worse if Fallout 4 is made strictly for the iOS and Android platforms.
As for the announcement, fans would prefer if Bethesda can reveal on Fallout 4 while on stage and not behind closed doors. The way where Doom got announced was so horrible that Fallout fans don’t want it repeated for Fallout 4.
While everything mentioned above might sound scary, it is worse if Fallout 4 turns out to be Fallout Online, just like The Elder Scrolls Online. That will be the biggest disappointment of them all and something Bethesda should not announce.