New academic work on spam suggests users would tolerate spam in exchange for discounts on connectivity:
"These results confirmed the researchers' hypothesis that users who pay high monthly service fees are willing to receive spam in return for obtaining a discounted rate".
Ummm. All this will do, in terms of competitive dynamics, is drive down the price of the discount, and thus drive down the 'price' of spam, forcing more spam to be sent for every ISP that does this.
Not to mention users really will hate it - no matter what survey results show.