Some group could not just change the blocksize. Instead, what can happen is that someone publishes a piece of software implementing a protocol - call this Bitcoin 2.0 - that can process all previous blocks correctly, but relaxes the rules for future blocks. People can then choose whether or not to run this piece of software.<p>However, Bitcoin is only <i>useful</i> because of the consensus on what the protocol is - so in practice, people must generally run whatever everyone else is running. At the moment, there&#x27;s a general consensus that everyone should be running software implementing the same protocol as the latest version of the Bitcoin software implemented by a certain group of people. That could, theoretically, change if the majority of the community doesn&#x27;t like some change to the protocol, forcing the dissenting minority to follow along with them.