What is more interesting is the reduction in revenue through gasoline taxes. In most cases, this is intended to go towards road maintenance.
As for more bikers, I don't see how this could be a bad thing. In most cases, the spacing that 2 cars take up could fit 4 bikes or so? factor in that more secondary roads will be utilized as opposed to main roads, meaning traffic would be more evenly distributed, and I think it would not be that bad.