...the 1Mb limit is reached and transaction delays occur to such an extent that the chaos and negative press stops enough people from using bitcoin that it can limp along with saturated 1Mb blocks.
I already outlined the likely scenario describing what happens when transaction volume reaches the max block size limit:
we should see what happens as we run into the soft blocksize limits...what do you predict will happen?
In this order:
1. Most blocks are at or near the 250 kilobyte soft limit.
2. The memory pool of transactions grows due to insufficient space in blocks.
3. Users notice trend of transactions taking longer to confirm, or not confirming at all.
4. Fees increase as users pay more to improve confirmation times.
5. Miners (or mining pools) modify code to select transactions with the highest fees per kilobyte to fit into blocks. They remote the 250 kilobyte soft limit. Some miners disallow free transactions entirely.
6. Transactions clear much more quickly now, but fees decrease.
7. Blocks increase in size until they are at or near the one megabyte hard limit.
8. Fees start increasing. Free transactions rarely confirm at all now.
9. Small transactions are eliminated since they are not economically feasible. SatoshiDice increases betting minimums along with fees. The volume of SatoshiDice transactions decrease.
10. Users at the margins of transaction profitability with respect to fees are pushed off the network.
11. Many people, most non-technical, clamor for the block size limit to be lifted.
12. Fees reach an equilibrium where they remain stable.
13. Spurred by the profitability of Bitcoin transactions, alternate chains appear to capture the users that Bitcoin lost.
14. Pleased with their profitability, miners refuse to accept any hard fork to block size.
There will be no "chaos" or long transaction times, just high transaction fees. Users for whom it makes economic sense to utilize the Bitcoin network will pay the fees. Everyone else will use alternatives which are guaranteed to appear for economic reasons. If Bitcoin's transaction volume requires fees that are so high that some people get pushed off the network (like SatoshiDice) there is clearly a market for payment networks.
We should be so lucky that we get transaction volume sufficient to drive up fees to where users look for alternatives. It means Bitcoin is doing something right!!!