I think a career in CS is already sufficiently attractive, for monetary and other considerations, that those who have a great potential and a passion for it already choose to pursue it.
So if we increase salaries a lot and this results in more people going into CS, I think it's pretty safe to say most of those additional recruits will be more in it for the money and less because that's what they should pursue, thus reducing the overall quality.
If programmer salaries went to 200k overnight, do you think the quality of undergrads would go up or down?
It would obviously go up or stay the same, following your logic. Even if the proportion of good programmers out of CS programs decreases there is no reason the real total number would go down.
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If anything, the new influx of interested students would maybe counter a little the need for CS departments to dumb down the curriculum in order to stay above whatever arbitrary number.
Maybe it would result in less JavaSchools. ;)
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Sadly, increasing quantity will probably have little impact on increasing quality.