My opinion from being more of a car guy is that the nostalgia buyers old enough to have disposable income and to reminisce about "easier" times are aging out of their market and the next generation is more interested in what they remember from when they were kids. I'm thankful that I never suffered from this fiscally-damaging and sometimes emotionally-stunting disease and merely had PTSD (ironically, though I believe I may have been spared from nostalgia as we refer to it today by PTSD, the original idea of nostalgia was that of a "soldiers' disease" and very much linked to early recognition of what would be known as PTSD). Good bikes, like cars, will sell because they have qualities or iconic image that has timeless appeal, but mass produced mediocrity or outright junk that was overvalued by nostalgia buyers will come down and likely stay there. A Ferrari 250 GTO transcends fads, but utterly ridiculous 7-figure sales for 'Cudas are over. Right now, the average-among-its-contemporaries-when-new Supra is on the rise, but when the Fast-and-Furious-appreciating generation ages out, I'm sure the value of those will fall back, too (assuming trends continue along their historical paths until then, though that looks unlikely).