This market certainly went crazy price-wise but then, as the author pointed out, tanked. It basically tanked because everyone started collecting the cards. Like any collectible market, it mainly took off to begin with because no one was collecting these things and keeping them in mint condition. The realization of that then created oversupply.
I can't speak much for that market but in the past year Pokemon in particular has exploded, to the point where the the ratings companies where so inundated with submissions that they had to stop accepting them.
The Pokemon market seems to have cooled but prices for mint condition first edition cards still seem to be pretty high. It's impossible to predict where this market will go just like any collectible market because it's so driven by market sentiment.