Although when something is momentarily hot, and gamers flock to it even if in reality it is a lacking product; (as we see with Oblivion and now Fallout 3 to an extent) over time I have faith that lack of evolution will catch up to the company failing to evolve. It just takes longer for the mainstream. Albeit Fallout 3 may be forgivable in some regards, it is behind the times in many, and a game using the same engine two or more years from now that is already lacking will finally see a decline in fans. (barring some other innovative miracle) Who knows what competitors there will be either? I always like to use the Tony Hawk franchise as the example since they reached a point of recycling the same game over and over until one day another company released something better. Hawk lost fans who went to the new game forcing the original franchise to finally progress again in an effort to win back those lost.
I imagine this is how Beth is. Even though there may be developers within the company who care about their product, Beth seems to want to only push as far as they can get away with, instead of taking pride in advancement. This isn't to say that everything they do is trash, but it doesn't feel loved; at least, not by the ones in charge. I am sure just by walking within the new Fallout world, one can tell where someone cared and where someone else didn't.
We'll see though, maybe Bethesda will surprise us in the future. I'll tell you, I was never into anything Beth had done before, but a severely updated Oblivion would interest me. Nothing wrong with the concept. I would have bought Oblivion itself if it hadn't of been so poorly executed. (don't get me wrong fans, I do understand why you like it)
EDIT: I don't know a lot about game/graphic engines and all of that, but there are already a lot of options out there besides using this thing that Bethesda is, isn't there? My favorite thing so far has been the use of this motion capture with the Rage/Euphoria engine that GTA IV and I believe Force Unleased uses. Things behave almost like real. Far Cry 2 has a great fire system and up-to-date explosive objects/behavior. Killzone 2 will be making use of all of that I think. It just makes me sad to think how much better FO3 would have looked/been with those things intact. I mean, we don't even have shadows. (shakes head)
I think I'll enjoy the game, but it's like watching Mad Max, and instead of Mel Gibson we get Ben Affleck.