there are a couple of points to consider here:
1. it was not a "Japanese system," as the OP says, it was an offer from a commercial company in Japan who probably took out insurance to pay for it. it was also a lot more than $100,000. it was one hundred million Yen which works out at $890,317 at today's exchange rate. so offering only $100,000 to an American seems pitiful by comparison.
2. the suggestion that there are out there somewhere one or more Americans who could break 2:10 but have not yet done it because there is no advantage in it for them, but who would do it if there were serious money on the table, seems wrong to me on a number of different levels. it seems insulting to Americans generally, and to distance runners specifically. are you suggesting they are only motivated by money. whatever happened to Kudos?
3. if this were to work, does that not suggest that this would have been a much better route than the one adopted by the Nike Oregon Project, and much cheaper? instead of investing tens of millions of dollars in building a state of the art training facility, equipping it with underwater treadmills, altitude rooms, security staff and 24-hour floodlights and video monitoring on the tree-lined track then staffing it with top line coaches who hand-pick their athletes for one-to-one coaching, and, let's not forget, incurring the wrath and suspicion of the running community for their progress. instead of all that, you just announce a money prize for breaking the American Record and let the guys go to it themselves.
would you be prepared to contribute towards the prize fund?