The solution is to make it 'capitalistic'. Change all of our internet contracts from Unlimited (up to 'x' GB/month), to a simple $/gb cost.
It would be in the ISPs best interest to provide their customers the fastest internet connection as possible. E.g, if a customer can stream a 4k video vs SD then the ISP would make more money per unit time.
Think of it this way, if comcast charges $0.25/GB, and a netflix SD show is say 1GB and HD is 4GB, then comcast grosses $1 for HD and $.25 for SD for the same customer streaming request.
Over time its likely the price per GB would decrease, just like it has for cellular.
On a more evil side, this would also stop chord cutters. Pirating content is no longer 'free', and Netflix would cost significantly more than $10/month ($10/month + 'x'GB * $/GB).
As for what rates to expect, if comcast charges in ATL $30-55 for 300GB, that'd be about $.10/GB to $.20/GB. As for speed tiers in a $/gb system, your guess is as good as mine.