It's driven by the spending power of aging boomers. When they run out of spending power and move into fixed incomes, or the prices get beyond what they want to spend, or they learn to be happy in age instead of wanting to be young again, it will burst. Because that is what happens with all nostalgia driven hobbies (just look at model trains and kids that grew up in the '40s for a trend). There's no way it will go on forever because it's largely driven by the nostalgia of an aging demographic trying to recapture the things that made them happy or that they lusted after in youth. Can't be with the football cheerleaders anymore but dammit you can buy the stereo you wanted for cheap. Even the younger people into it are riding the nostalgia bubble, lusting after the rose-tinted romanticizing of a time they were too young to remember, like the kids in my high school in 1992 wishing they'd grown up in '72 to be there when Zeppelin was playing out. When in reality it was probably a lot more "You Light up my Life" on the airwaves than Robert Plant.
