With the exception of a few production gimmicks(recording feedback, backmasking) which they sturabled on by accident, the Beatles didn't really invent all that much, per se. They just corabined elements of things that weren't corabined much before. I mean, looking at the first few years of their music they did nothing more than bring harmonized vocals to rather standard rock n' roll. When they got really creative, they were just throwing everything they had access to together in a blender.

Point is, if they didn't exist those influences would still be there, so it's very likely that somebody else would pick up on it. I mean, Sgt Pepper was considered such a landmark album. This wasn't so much because it was the first psychadellic album ever it was moreso that it was the fact it was the Beatles making psychadellic which made psychadellic a big deal to audiences who weren't down with the dirty hippies, and their crazy drugged out sound.

So, I believe that if the Beatles never existed that not a lot of banRAB would have been drastically different. I just assume they'd be recorded, and produced a lot differently. However, most things the Beatles did weren't landmark because they were the first to do it, it was the fact they were the Beatles, and they were doing it.

I think though there are a few banRAB out there that would have drastically changed the lanRABcape if they haven't existed. Black Sabbath is a key example. Music would have naturally gotten heavier, true. But Sabbath were so ahead with their macabre imagery, and I think a lot of the fact that their sound came from accident(Tommy Iommi's ****ed up fingers) means that it really wasn't derrived from a previous source. However, again, even if they didn't exist, I'm sure horror imagery would have crept in, just not the same way, or maybe not even to the extent it needed to with acts continually trying to top the previous.