I agree that we are in a bubble. I've thought the same thing for a while. We just had a discussion that Earthbound was artificially overpriced. Moreover, the amount of limited editions is beginning to get similar to the foil cover comics of the 90s. The thing that really makes me think that there is a bubble is the amount of collectors who buy new, and leave the game sealed while it is in their backlog, and check prices before they start playing. This is the definition of prospecting. Either you would open it or you would wait until you were ready to play. Games decrease in value SO quickly now. Wait two months and you can get most games for $20 on amazon. It would be cheaper in the long run.
The collecting won't die but it will become more niche. This happened with comics. They are from from dead. When I lived in Denver I would frequent mile high comics. One of the biggest stores I have ever seen. In Tulsa, there are probably 20 comic shops (This is counting vintage stocks). But the prices are no longer unbelievably insane. I have purchased crazy awesome comics I thought I would never afford back in the 90s. This is the collecting I like.
I actually grew up a Nintendo kid. The genesis started winning me over and the Dreamcast cemented my love of SEGA. But one of the main reasons I collect for the Genesis is that if there was a bubble for that, it already popped. I have been picking up carts for a quarter. I recently picked up X-men 2, comix zone, rocket knight adventures, vectorman, and batman and robin in a bundle for $5. I can't do this as easily with Nintendo. I for one would welcome a bubble burst. Earthbound is not worth $200 cart only. I do not know of a single saturn game that is really worth what it goes for complete.
Comic collecting is live and well. It just left the mainstream. I do not miss stores being filled with prospectors. I do not miss paying $6 for a common back issue. Back issues should decrease in price, not increase. Moreover, the comic collecting community is tighter than ever before. I would not complain if the game collecting bubble burst.