I'd like to see an expansion dedicated to the aliens, as in Fallout3 with Mothership Zeta. In the world of Fallout, there was fine, a parenthesis in this sense. Perhaps adding some mission more than the DLC Fallout3, but always set in a beautiful spaceship. Also, I'd like to get back the Geck tool; I too enjoyed creating maps of alien base, and I'd do it again with Fallout4. What do you think?

Aliens, no idea if they will be in. I personally didn't like Zeta so I hope not but who knows. As for the Geck, yes the developers will release that sometime around Jan-Feb of 2016

Oh thank you so much, for the info of Geck. I hope easy to use, as the old one. For the aliens, if they are added through a dlc, the user is free to not take it if he does not like the theme. But for me, Fallout without the alien presence, is not complete. (like Fallout NV) I hope that for once, I can see in a game all the things that I like; Fallout 4 will become the greatest game of all time, for me.

In an interview the game wont release with the GECK, aparently they hadn't even looked at making it yet and aren't sure how they'll be able to make it work for PCs and consoles.