Chances are most of the network would upgrade to it with no questions ask. All the naysayers would be left in the dust and with a fork that wouldn't even be worth a nickel per coin.
Yes, but these new nodes would still accept the smaller blocks as well. It will only work, when the longer chain created consist of larger blocks.
Assuming the chain that accepts larger blocks has at least 49% of the hashing power, the blockchain would most likely split as soon as the first block larger than 1MB was mined (making it immediately the "longer" chain by one block).
As long as the "small Block" Chain has more than 50% of the hashing power, wouldn't it eventually end up to be the longer chain again?
As old Nodes wouldn't accept Blocks from "Big Block" Chain the split would occur as soon as this chain has the majority (>50%)?
I might have my math messed up a bit here (it's early and I'm not much good at logical thinking in the morning), but if the "big block" chain has >49% of the hashing power and adds a block before the "small block" chain than there is roughly a 1% chance that the "small block" chain will add a block before the "big block" chain adds a second.
At that point the chains will be equal length, but the "big block" chain will have already been working on its next block for the entire time that the "small block" chain was trying to catch up. The chance that the "small block" chain will add two blocks before the "big block" chain adds one block is something like 0.01% right? So yes, this means that "eventually" that 0.01% chance should add up over time and the "small block" chain would pass up the "big block" chain.
However, how long is that likely to take? Is my math right if I estimate 5,000 blocks for a 50% chance of passing up the "big block" chain? Isn't that 34 days? If the "big block" chain stays longer for a month, how many people will "jump ship" from the "small block" chain to the "big block" chain during that time if the "big block" chain is starting to look like a permanent fork? Enough to increase the hashing percentage from >49% to >50%? If so then it becomes likely that the "small block" chain will not catch up.
Of course, I suppose it is possible if the split stayed anywhere near 50% that the "big block" chain could remain only a few blocks ahead of the "small block" chain. Then 6 months later with a small run of luck the "small block" chain could suddenly overtake the "big block" chain and BAM 6 months of blocks orphaned on the "big block" chain. Since some of those inputs will have been spent elsewhere on the "small block" chain you'd have transactions lost to double-spends all over the place. What a mess. Seems like as soon as a "big block" was mined, a release would be quickly offered with a checkpoint to prevent something so devastating from happening, right?