If I lose direct access to the blockchain then I am forced to hand over all my wealth (not just enough funds to cover trivial purchases) to a third party.
That's probably the best argument I've seen. I think of how today I have many paper wallets, mobile wallets, and hosted (shared) E-Wallet services (i.e., custodial services) where I had a balance of a few millibits or less in them and won't (or can't) withdraw because the Bitcoin network transaction fee is prohibitive for that small amount of bitcoin. Now as fees rise due to scarcity of empty space in blocks then I'll essentially have permanently abandoned those wallets with the small values (i.e., those funds become economically unspendable, ... worthless!).
I suppose for the paper wallets and mobile wallets where I have the private key I could combine them into a single transaction without incurring a higher fee, but that's possible only today because there's still some low-cost space left and the fee required doesn't rise linearly when the size of the transaction rises. Without a fork then eventually we are essentially paying a fee for each additionally byte and the resul will likely be that millions of UTXOs with small amounts (e.g., sub-millibit -- less than 0.001 bitcoins) will become worthless. Hey now, that's some real money we're talking about discarding! [Anyone care to crunch the numbers -- what is the sum total of bitcoins that exists in UTXOs under one millibit?)
It makes me think back ... First they came for the dust, and I didn't speak out because I didn't play SatoshiDICE. When this day comes (when the 1MB cap is reached, and no-hard fork), maybe a millibit becomes the new dust! And then let's say the fee required rises even more, maybe UTXOs under 0.01 even become economically unspendable. That becomes a real problem for most of us!
So what to do?I'ld like a Bitcoin that can scale and grow with transaction demand. I'ld also like my car to get 150 MPG. The latter can't happen simply because a gallon of gasoline doesn't have the energy needed for an internal combustion engine to propel today's car for 150 miles. Now I'm not entirely convinced the former can happen either. That's because a hard fork that doesn't have the consent of the Economic Majority (
http://en.bitcoin.it/wiki/Economic_majority ) will fail.
Let's go through the first hours of the hard-fork. Let's say it happens at block 400,000 (a lttle over a year from now). Everything was in place -- miners with the right nVersion indicating consent was well above the threshold (e.g., 80% of last 1,000 blocks had nVersion=4). But ..., I'm not willing to believe that exchanges, merchants, merchant processors, etc. are going to themselves take on the full risk of double spending that would occur if the hard fork eventually fails (maybe a day or three later even). The only way to prevent the double spending that would result would be to require that a transaction confirms on the block chains on both sides of the fork. So these entities are going to watch both sides. Well, a transaction that has any taint from a coin generated on the side with the larger block size rule change (I hate calling them "gavincoins", but for the purpose of this argument that name is short and everyone here knows what it means) will not confirm on the other side of the fork where the 1MB limit is still followed.
So the market instantly realizes this difference between a Bitcoin and a GavinCoin. So the value of a GavinCoin will drop relative to a Bitcoin. Miners can't convert or spend these newly mined coins nearly anywhere, so all you have is buying from speculators. Now those mining on the side which still recognizes the 1MB max limit are still mining blocks (albeit at a much slower rate because of the dramatic loss of hashing capacity) and some market for those newly mined coins exists -- again, thanks to speculators. Things can flip quick. Maybe a day goes by and all of a sudden a large amount of hashing capacity switches back to the 1MB max side due to the dropping exchange rate of GavinCoin, and it becomes quite possible (if not probable) that the 1MB limit will be with us for some time longer.
The exchanges and merchants that played both sides (i.e., required confirmations on both sides of the fork) lost nothing as either way they have confirmed transactions on what is eventually the sole winner. If the hard fork fails then the losers are those who had E-Wallets (custodial accounts) and found their pre-fork bitcoins were spent and they only end up with tainted GavinCoins that can now never be spent (at least not anywhere near parity with a bitcoin). Likely most every custodial service (e.g., exchanges, hosted/shared eWallets, etc.) that didn't require confirmations on both sides of the fork ends up bankrupt as a result of getting dumped on with GavinCoins while allowing withdrawals of untainted bitcoins.
I just don't see how a hard-fork succeeds. There is risk of accepting GavinCoins. There is no risk (excluding exchange rate risk) of putting your own pre-fork coins into storage for a (long) while and not letting them become tainted GavinCoins (as they can still be spent a year, two or ten later).
[Edited: A couple small readability changes.]