I doubt we will see a Fallout 3 (Which would suck) since the 3 main creaters no longer work for Interplay.

They have started there own company Troika and have released Arcanum a while ago which seems to expand a bit on the Fallout game play style and they are now working on Dungeons & Dragon: Temple of Elemental Light which will again have the Fallout style of gameplay

Zagreus sits inside your head Zagreus lives among the dead Zagreus sees you in your bed and eats you when you're sleeping Zagreus at the end of days Zagreus lies all other ways Zagreus comes when times a maze and all of history is weeping