Fallout 1 and 2 are good, yes. They could probably do decent in today's market, if not just for the fanbase.
Just, look at Fallout 3 for what it is. I think it's a great game. Probably the best console game I've ever played. Ever. I love it. I want to have it's children.
But, as a sequel...
I'm almost positive I've seen dog meat and bloatfly meat in super mutant encampments.
My guess is that they eat what they can get their hands on. If a dog walks by, shoot it and eat it. If a wastelander walks by and they're feeling hungry, why not?
Like which? Let's run off a list.
SPOILERS AHEAD
Megaton has huge walls to protect from raiders and other beasties, all of the citizens carry weapons and they have a sniper on the roof. They also have plenty of food, judging from the two restaurants that are in operation.
Rivet City is...