Personally, I'll be happy if Fallout 4 looks even as pretty and atmospheric as I found Skyrim (actually Skyrim almost ruined Skyrim for me because all it made me want was a Fallout game that looked as nice...) And from what I've seen in previews Bethesda looks to have surpassed that.
Maybe I am getting old, because I'm still amazed that character models have fingers instead of just block-hands (hell, I'm still amazed that games have more than two colors...)
One thing that gets overlooked a lot by some of the folks who want to focus on the graphics instead of any of the myriad gameplay and ruleset changes that Bethesda's bringing to the table is the difference between art design and graphics power. They're not the same thing.
I remember when everyone was talking about the first Crysis because it's big selling point was that it would just about melt your computer if you tried to run it at full settings. But to me it just looked like any other bland sci-fi shooter. Sure, it had plenty of graphics power, but no art direction to back that up or set itself as visually distinct from any other game that played just the same.
I have my reservations about some of the gameplay choices Bethesda has made with their games over the years but I've never been able to fault them for anything short of downright admirable art design and attention to detail. If they're not necessarily pushing the "graphics" from a technological standpoint I still feel they pretty much set the bar in terms of art direction for these sorts of games. There was quite a bit I didn't think Fallout 3 quite accomplished even to their own objectives (and more that I just subjectively didn't approve of,) but I have to hand it to them - visually I felt they not only hit the nail on the head in terms of creating an iconic open world in the Fallout universe, I think they went beyond the original Fallouts in terms of creating something visually distinct and iconic.
I do remember when Morrowind came out, that was a big step forward in games like this. That was the first real 3D world that I could play in an RPG context and explore with that level of detail. No one was doing the "every item you see in the game is it's own object that can be manipulated and used," at the time - and even now in most games if you see a shelf with a bunch of items in it, it's all one model; the level designers aren't painstakingly placing every random tool and piece of string into the level one by one. I recall being just blown away by Morrowind. And then I went into a house and looked up, and realized that Bethesda was putting more thought and detail into the ceiling of one type of house than other developers were in entire levels.
These days, maybe they're not reinventing the wheel, graphically, every single time - but I believe they are still putting as much passion into the art direction as they always have. They make very pretty games, I think, and wonder if those who don't see what I see just can't see the forest for the tree.