Bitcoin actually has this "magic" property of being very, very hard to change. It is derived from community extremism against changes and from the huge number of players who would need to agree and then huge number of existing deployments that are very slow to upgrade.
Bitcoin is hard to change the similar way TCP/IP protocol stack is hard to change.
It's easier than you think. Just five organizations command >50% of hashpower[0]. I don't think it's likely to change soon but it's not out of the realm of possibility, and it's not even the most decentralized cryptocurrency in terms of difficulty to enforce new network rules.
Bitcoin is hard to change the similar way TCP/IP protocol stack is hard to change.