It can be phased in, like:
# if ( blocknumber > 115000 ) # maxblocksize = largerlimit
It can start being in versions way ahead, so by the time it reaches that block number and goes into effect, the older versions that don't have it are already obsolete.
When we're near the cutoff block number, I can put an alert to old versions to make sure they know they have to upgrade.
– Satoshi, Oct 04, 2010 1)
I'm the guy who went over the blockchain stuff in Satoshi's first cut of the bitcoin code. Satoshi didn't have a 1MB limit in it. The limit was originally Hal Finney's idea. Both Satoshi and I objected that it wouldn't scale at 1MB. Hal was concerned about a potential DoS attack though, and after discussion, Satoshi agreed. The 1MB limit was there by the time Bitcoin launched. But all 3 of us agreed that 1MB had to be temporary because it would never scale.
– Ray Dillinger, Feb 07, 2015 2)
Gavin is right. The time to increase the block size limit is before transaction processing shows congestion problems. Discuss now, do soon
– Andreas Antonopoulos, May 5, 2015 3)
A lot has changed in the 426 days since that tweet.
– andreas antonopoulos, Jul 5, 2016 4)