Students as Investments?

We all may (or may not) know that the President wants to see an evolution of the education system, where merit and quality are enhanced for both teachers and students.

I got this from the Freakonomics blog from the NY Times (from Planet Money blog on NPR)
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What if teachers were paid based on the future income their students make. For example, student A grows up to make 100k a year. We look at the records and find the 20 teachers that taught student A and compensate them based on that. Compensation could be based on number of months spent with student.

That way the students would turn into "investments" for the teachers.
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I'm curious what you all think about this. Some questions come to mind:

1. What benefits could come out of compensating a teacher for a student's future earning potential?
2. What are the downfalls (could this benefit some teachers of areas that generally earn more than others [ie: arts teachers versus business teachers]).
3. Is this method of compensation flawed from the beginning (equating quality of education with money earned--some careers just don't pay as much as others, regardless of how talented you are)?
4. How else can student/teacher productivity be related to encourage high quality, meaningful education and educators?

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a.Rias
http://poli-babble.blogspot.com/