Satoshi Nakamoto decided upon a one megabyte block size limit for Bitcoin. He viewed it as a temporary measure, but because it has remained fixed for so long it can reasonably be considered by some as a permanent limit. This means currently that the Bitcoin blockchain can not grow faster than 1Mb every 10 minutes.
If the limit remains fixed then Future A will be the road ahead. If the limit is raised or set by an algorithm, then Future B lies ahead.Future A: Bitcoin will never handle more than 7 transactions per second. This is a tiny fraction of that handled by major payment systems. Evenutally 99+% will need to be handled by third-party services (such as Coinbase), bitcoin "banks", trusted transfer layers or even alt-chains. Only large transactions (with high fees) get included on the main blockchain. Bitcoin never makes large payment systems obsolete (Visa, Mastercard, PayPal) but full nodes can be run by individuals with moderate computing power and bandwidth. People can personally verify the integrity of the bitcoin network, even though it operates analogously to an internet backbone, but for currency, and people's transactions and holdings are held elsewhere. Mining the main blockchain will remain a niche business,
Future B: Bitcoin grows to handle hundreds or thousands of transactions per second. Perhaps Moore's Law can keep up so that some individuals can run full nodes, although lightweight nodes will be necessary for nearly all. Big companies run nodes. All transactions which people want to have on the main blockchain (with low fees) are supported. Third-party services do not have to be used unless they add value, faster confirmations, etc. Existing large payment systems will wither. Mining the main blockchain will become a big business.
It is fair to say that this subject has been exhaustively discussed in many threads. There are many arguments for and against, so people are invited to wade through the history of the debate before deciding to vote.
Any change will require a hard-fork i.e. everyone will need to upgrade their software. It will likely be necessary before the end of 2013 based upon transaction growth rates. Of course, if no change is decided upon then the limit will become a real constraint, fees will rise, zero-fee transactions will no longer be processed, third-party services must fill the gap.
Jgarzik > [PATCH] increase block size limit
https://bitcointalksearch.org/topic/patch-increase-block-size-limit-1347caveden > Block size limit automatic adjustment
https://bitcointalksearch.org/topic/block-size-limit-automatic-adjustment-1865barbarousrelic > Max block size and transaction fees
https://bitcointalksearch.org/topic/max-block-size-and-transaction-fees-96097Jeweller > The MAX_BLOCK_SIZE fork
https://bitcointalksearch.org/topic/the-maxblocksize-fork-140233Misterbigg > Why do people pay fees? Why are free transactions accepted by miners?
https://bitcointalksearch.org/topic/why-do-people-pay-fees-why-are-free-transactions-accepted-by-miners-144421Retep > How a floating blocksize limit inevitably leads towards centralization
https://bitcointalksearch.org/topic/how-a-floating-blocksize-limit-inevitably-leads-towards-centralization-144895notig > The fork
https://bitcointalksearch.org/topic/the-fork-145072hazek > Why the Bitcoin rules can't change (reading time ~5min)
https://bitcointalksearch.org/topic/why-the-bitcoin-rules-cant-change-reading-time-5min-145475