The only thing needed to hurt the retro game market is a few major or even semi-serious collectors getting out at the same time. You can already see examples of this on ebay when there is a few of the same "rare" games on auction at the same time. They generally will not sell nearly as high as comparable buy it nows, or even as other sold results. A great way to correct a games inflated value is to introduce just a few copys of that game into the market at the same time.
Lets face it, as rare as "rare" games can seem, there was generally still tens of thousands made, if not many many more. They truly are not that rare, there is just a lack of available copys on the market at a given time.
But now also a factor, just like with comics, since we cant base the value on a items true scarceness or rarity, we then assess a value on its condition instead. Which sometimes seems insane to me. But does play right into the generalized ever increasing analness of collectors as time goes on...Which seems like a never ending battle with ones self. (IE. This Marios sealed 8.5 condition is not good enough I must have a even better one).
But, If this guy can convince people to speculate that sealed games will be the next big big thing like a Warhol painting, then who the hell knows. But there still will always be more then just a few in existence, It will never be a original unique painting. I think market correction could be drastic, swift, and easily happen. As much as you think that sealed game is uber rare, there is probably for example, at least 50 other collectors out there with the same thing. As we all age, loose interest, die off, need money, these rare items will emerge no matter what.
It seems to be a truly risky investment if that is how one was to look at it.