Could the 1MB block size limit be replaced with a growth-dependent limit? From what I have read (here, for example) the 1MB limit is to prevent spamming of the blockchain. And if/when Bitcoin becomes more widely adopted we will have to increase the limit so that the network can handle more transactions per second.
Instead, could we have a rule like "blocks can be no larger than 1.5 times the average of the last 100 blocks"? The hope is that we could automate this spam prevention measure while still allowing for growth. Has this idea been considered anywhere else at all?
Maybe this be too large of a protocol change. Would we be able to get everyone to update their nodes to follow the slightly altered protocol?