Having looked through the thread, it looks pretty cool, and I like the Retrofuturism. It feels like real Jetsons style, which I think that would be a good contrast with the destitution and seediness that you'll inevitably be wading through.
If they wanted to mimic the original Fallout Games though, I'd say my main point of feedback would be, keep it abstract:
1. The Sprites seem too detailed and standardised for my tastes. One of the great strengths of Classic Fallout is that the homeless sprite, and the businessman sprite, and the prostitute sprite, and the man and woman in burlap sprites, were all intended to represent lots of different people, and all looked, walked, ran and acted in different ways, which meant these sprites were very good for what they were intended to do: Give immediate vibes of the character you're speaking to, and how you should read them before you've even spoken to them. These sprites are more visually distinct sure, but I can't get an immediate read on them.
2. I'm not sure about having the character's portrait always present in conversation and at the bottom of the screen DOOM style. Having the player character be an abstract model that you can project onto, again is the great strength of Fallout 1 and 2.
3. We've only seen part of the 3D Combat - But I hope that they make that so the fights in the 3D space aren't a 1:1 recreation of the environments of the 2D Space - They should really give themselves flexibility on that.