Without a sharp constraint on the maximum blocksize there is currently _no_ rational reason to believe that Bitcoin would be secure at all once the subsidy goes down...Limited blockspace creates a market for transaction fees, the fees fund the mining needed to make the chain robust against hostile reorganization.
I agree that there needs to be scarcity. I believe that tying the scarcity to the average amount of tx fees assures that that block size can grow but also that there will always be a market for tx fees.
I strongly disagree with the idea that changing the max block size is a violation of the "Bitcoin currency guarantees"...It's not totally clear that an unlimited max block size would work.
I agree. It seems obvious that if the max block size is left at 1MB, and there are always non-free transactions that get left out of blocks, that the fees for transactions will keep increasing to a high level.
Each node could automatically set its max block size to a calculated value based on disk space and bandwidth
Not really a fan of this idea. Disk space and bandwidth should have little to do with the determination of max block size. Disk space should be largely a non issue: if the goal is to make Bitcoin more useful as a payment network, we should not be hamstrung by temporary limitations in storage space. If bandwidth is an issue then we have bigger problems than max block size - it means that the overlay network (messages sent between peers) has congestion and we need some sort of throttling scheme. If the goal is to make Bitcoin accommodate as much transaction volume as possible, the sensible choice is for nodes to demote themselves to thin clients if they can't keep up.
I just think miners should be able to create their own limits together with multiple "tolerance levels"...That would push towards a consensus. Miners with limits too different than the average would end up losing work.
This doesn't make sense. Given any set of network parameters, there is always a single global optimum strategy for miners to maximize their revenue by prioritizing transactions. Tolerances for block sizes are not something that miners will have a wide variety of opinions on - the goal is always to make money through fees (and the subsidy, but that doesn't change based on which tx are included). Besides, why on earth would we want to waste hashing power by causing more orphans?
If the blocks never get appreciably bigger than they do now, well any half-decent laptop made in the past few years can handle being a full node with no problem.
If Bitcoin's transaction volume never exceeds an average of 1mb per block then we have bigger problems, because the transaction fees will tend towards zero. There's no incentive for paying a fee if transactions always get included. To maintain fees, transaction space must be scarce. To keep fees low, the maximum block size must grow, and in a decentralized fashion that doesn't create extra orphans.
the best proposal I've heard is to make the maximum block size scale based on the difficulty.
Disagree. If this causes the maximum block size to increase to such a size that there is always room for more transactions, then we will end up killing off the fees (no incentive to include a fee).