Fallout has a huge legacy, believe it or not. They did the same thing with FO3. If history serves us right, then FO4 will be even better. The FO games get progressively better with every iteration. I just hope they stick to it's roots. IMO the best thing that they could do is recreate the whole FO2 world and base the story in those times, having the same NPCs, towns, etc. That would be awesome!
The original Fallout revolutionized the RPG genre and Fallout 3 really showcased a step-up in open world design. I'd love to revisit the iconic locations in the first two games in 3D with modern technology. I wish Obsidian or Bethesda would remake FO1 and FO2 with the gameplay of FO3/New Vegas. At least someone is trying: