Augh, gawd.
The only solace can be found in that, back then, Bethesda wasn't so crazy right after Oblivion - though the Horse Armor is infamous, Shivering Isles and Knights of the Isle were a step in a better direction, so the facepalm writing might be of a less rampant feature, but countered by seriousness.
I say this because the plot of Fallout 3 itself as we have it was utterly weird. We need to find our dad who is trying to bring clean water back to the wasteland because apparently the water cycle itself is irradiated or simply doesn't exist and the Enclave comes in to hijack it to kill off the dirty wastelanders.
On the west coast, the Enclave is dead, there's civilization there, the brotherhood is on the decline, but I think they would had kept the first thing while amping the latter thing - maybe even placing the NCR-Brotherhood war as the plot itself. Think about it - it'll allow them to keep the oh-so-cool Brotherhood, have the region decimated by the war, allow the player to, like in Skyrim, choose a side, and either bring the BoS to victory or the NCR. How good the writing for such a thing would had been fully depends on the writing team of the time, so, I'm going to say the same as 3. It would had been overall the same, though a lot more canon might had been ignored or changed and that wouldn't had gone down so well, while still producing a corporate profit and setting the stage up for more games.
