Technically it's possible just not plausible. Making a AAA game costs a massive amount of money compared to the money being raised on kickstarter, and that doesn't even include the even more massive amount of money needed to market the game. So would it be possible to raise, say, $25M on kickstarter? Sure, but it's not remotely plausible. You would have a higher chance of winning the lottery or getting struck by lightning twice in the same day. Even if you found a bunch of incredibly rich people, you'd still be talking at least 2500 people donating $10,000 each. That's just not even remotely plausible.
Possible yes, but so is a falling piece of meteor landing directly in your coffee cup. Doesn't mean it will happen.
You're overreacting a little bit. 2'500 people a $10'000 is the same as 250'000 people a $100. And its NOT impossible that Kickstarter could reach such backer numbers in the future the more established it gets. After all, 250'000 copies sold of a bigger game counts as rather low. (Of course in that case I doubt the average would be ~100)
I agree at the moment its implausible and Kickstarter probably will not be used for such big numbers, I just disagree with your reasoning.
The chances are nowhere near as low as the examples you describe.