1. More bugs! Radroaches and radscorpions and ants are cool, but how about a praying mantis? What about super-mutant butterfly behemoths? Maybe some they could have Harold's great-grandson being attacked by termites. Seriously Bethesda, I cannot believe you didn't release this game with MORE BUGS.
2. Motorcycle! Everyone knows the only thing cooler than scavenging the wastes for ammunition and food, is doing it on a 2008 Harley Davidson. Never mind the decayed and ruined roads, we'll stick some knobby tires on it, and it will instantly be suited for severe terrain situations.
3. All the guns from Fallout 1 & 2, plus a gun that shoots little nuclear bombs! Kind of like the Fat Man, except... well ok, so it's the Fat Man. Maybe put a scope on it this time.
4. More style! I think by this point, people will be bored of the same old ruined wastelands. How about we have a game set in a Caribbean resort untouched by war... except for the mutant bugs and the motorcycle.
5. This time, we need joinable factions in the game. I'm sure you'll be able to join BoS by #5 or so, and maybe you can be a ghoul a few iterations later. But at this point, I better be able to join and do quests for the Garden Gnomes.
Well, what do you guys think? What else should the devs put in? I'm sure they're already working on this, so input should be thrown in ASAP.