Again, we've already bumped up against the 250KB soft limit on several occasions; and amazingly, none of the miners have chosen to comment out that line of code.
It's been said a few times in this thread that there is little incentive to change the code as long as the block subsidy (25 BTC reward) is orders of magnitude larger than the total of transaction fees in the block.
I'm pretty sure that the 250KB limit has never been broken to date.
But it has. If you will go back to one of the earlier posts in this thread you will see that there is at least one mining pool with customized software that does not have the 250kb limit. You can also scan through the block chain and find plenty of blocks larger than 250kb. There are also a good number that have no transactions at all. The presumption is that these came from a miner whose only interest was in collecting the subsidy. As long as the subsidy is orders of magnitude larger than the total of transaction fees, this type of behavior will persist (as has been stated numerous times already).
Show me why you believe that this is so, not just your assumptions about what the future holds using overly simplified mental models.
Was this earlier post insufficient?
If we want to cap the time of downloading overhead the latest block to say 1%, we need to be able to download the MAX_BLOCKSIZE within 6 seconds on average so that we can spend 99% time hashing.
At 1MB, you would need a ~1.7Mbps connection to keep downloading time to 6s.
At 10MB, 17Mbps
At 100MB, 170Mbps
and you start to see why even 100MB block size would render 90% of the world population unable to participate in mining.
Even at 10MB, it requires investing in a relatively high speed connection.
It seems that all of your relevant points have been answered at least once so now I'm just being redundant, and no longer adding value to the conversation.