I have to say it might be good idea. Take acceptable artistic elements of all the Fallout games that seem original and reapply it to one whole game. There needs to be character development with at least 8 characters that can join your group. Just follow good plot, awesome storytelling, and have an epic atmosphere and you have yourself a REAL Fallout game.

Your best bet is to check NMA, as they are probably doing that right now with Fallout 3. They might run into a legal snafu, though. Remember when mods tried to remake Morrowind on Oblivion's engine? Copyright action put a stop to it.