Even though Fallout 3 and NV are in first person, they're still RPGs. You have to keep in mind that when you aim at something and pull the trigger, the game isn't relying on your skill as the player to make the shot, it's your character's skills that determine if you hit or not. People going into those games expecting a COD style FPS experience were disappointed. Now combat looks more FPS like, I just hope they don't remove the RPG part of it.
Pretty sure they have removed stat-based accuracy from guns. Though, they removed most of it in FO3 as well and instead focused primarily on scaling damage. In FNV, using iron sights basically gave you 100% accuracy and the game didn't suffer for it at all.
I'm actually okay with not having chance-to-hit in this kind of game. If it's real-time, first-person and requires aiming, chance-to-hit just adds an extra layer of annoyance. There was nothing less fun than seeing arrows pass right through enemies in Morrowind because of RNG. There's a reason why chance-to-hit was removed in Oblivion, Skyrim, DX:HR, etc. Hell, I'd argue that chance-to-hit is annoying in turn-based games too. Nothing quite as satisfying as getting screwed because your character missed an attack with 95% chance to hit.
The big question that remains is, how is the writing going to be? Is it going to be linear and stupid like FO3, or did they learn something from Obsidian? We already know there are going to be multiple factions, but there were two factions in FO3, you just didn't get the choice in which one you wanted to side with. Are the BOS going to be like the real BOS or FO3's knight's in shining power armor BOS?
Pretty sure the BoS are still the knights in shining armor that they were in FO3. Bethesda's writers aren't very good at moral ambiguity. If you go into FO4 (or any Bethesda RPG) expecting good writing, you'll be disappointed.