Prices will top out the moment people stop buying them. If that trend continues, they will go back to normal (normal being what they were 1-2 years ago). As long as people are willing to fork over 9-10k on a game, they will keep on climbing.

So you're one of the few that's going to drop 20k on a new game, maybe 30k? Not to burst anyone's bubble here but I've been around a long time and seen this all before. I remember when jukeboxes where the hot item, they were all going for a fortune, now unless you have one of the few collectible ones you can't give them away. Then it was woodrails, collectors only wanted woodrails, DMD games were going dirt cheap, now collectors only want DMD's. I remember when Pac-man machines were pulling 2k, some were getting $2500 for a stand alone pac-man. Try to sell yours for that now.
The collecting market is based on age, generally between 35-55 and whatever was nostalgic during your time. The pin market is very hot right now, but mostly specific pins, not all. Eventually the prices will get so high only a select few will be able to afford them, then the average collector will lose interest and find something else. Some collectors will get old and their games will collect dust. I got my first pin in 76 so I've been around the block a few times. These games will have little to no meaning to the next generation, they'll be collecting whatever they are into these days. The A titles will always hold their value, but once they get more expensive than new cars the market will fall apart. That is unless you're willing to mortgage your home for a 30 year old AFM.