*To increase max block size by n%, more than 50% of fee paying transactions(must meet a minimum fee threshold to be counted) during the last difficulty window were not included in the next X blocks. Likewise we reduce the max block size by n% whenever 100% of all paying transactions are included in the next X blocks.
This is a smart idea as it keeps the max block size to a minimum which still allows bitcoin to grow, so is TierNolan's solution. SimonL's solution seems a variation on this theme too. Even a pathetic solution: the 1000000 constant is changed to a 1000000 config variable (which can then be changed quickly) is an improvement over what exists today.
All I care about here is helping to prevent bitcoin hitting a wall.Thus far, all the scams, hacking of sites, lost/stolen coins etc are "user error". Despite all this bitcoin itself has performed perfectly, and this is regularly pointed out to critics. However, if transaction throughput chokes up due to the max block size limit then the "Great Bitcoin Failure of Late 2013" will be written in the history books. Critics will always be able to point out this event whenever bitcoin is promoted to new users. It will not be as good as "virtual gold" anymore, and that would be terribly sad.