In light of the ongoing debate on the Forbes thread, would anyone like to commit themselves in print as to how different segments of the market may rise and fall over the next 25 years? More specifically, how about at 5 year, 10 year, 20 and/or 25 year intervals?
Since this is my idea, I may as well go first. I hope I don't end up eating my words.
In 5 years, run of the mill 1970's work will show an actual decline, as it seems to now be doing. Same with 1960's work, except for important artists or key characters. But, kitchy stuff from the 1950's to 1970's will show a small resurgence--the sillier the better (in particular, romance or crummy horror). The trend will continue, with books from the 1960's to the 1980's peaking in about 15 years (prices may not drop, but sales will). In the next 20-25 years, the trend expands to cover the 1990's and 2000's. By the year 2040, this hobby starts falling in on itself in terms of pricing.