Although there have been References to Elvis since Fallout 1, with the high luck random encounter which nets you a Fuzzy Painting of him.

Back to the topic at hand, from what I understand and what has been mentioned if they had tried to get an Elvis song into the game we would have ended up with just that song and only that song as the entire song playlist due to how much they would have been charged to use it.

True but Fallout is a diverged timeline commonly speculated at 1949, so for all WE know what the world was culturally like apart from 1950s apparel and 1940s-early 50s music. So its hard to say how culture was specifically before the war.

Seriously? The velvet painting of Elvis has as much relevance as a ball gag. And if you feel the need to bring up 2077 then you completely miss the point. The actual year is irrelevant, the "theme" is everything.

See Napster as a big huge nuclear mushroom cloud of example why you can not distribute music, for free, without licensed consent from the copywrite owners......

You mean the p2p network that when shut down was replaced by a dozen other p2p networks? A few of which have been crushed in turn, but always with more popping up. But p2p is for end users. A commercial company doesn't have a snowball's chance in hell of getting away with selling copyrighted music without paying royalties.

True but nothing mentions Fallout timeline directly opposing ours. The best you could say is "Elvis might not be associated with Vegas in Fallout universe."