If, for whatever reason, all the mining power switches to the other chain, it will become the de facto "Bitcoin".
I don't know what the specific mechanism would be, but I would bet that it relates to the billions of dollars backing the current ecosystem, and the interests of the people behind them. If the right event or crisis comes along, then people could be compelled to switch over to something else.
I'm sure there's someone out there still mining blocks on that chain with the exploit from 2010, but that's not where the mining power is. If the right series of events occurs, the miners will switch.
> If, for whatever reason, all the mining power switches to the other chain, it will become the de facto "Bitcoin".
The miners do not control the network. The people transacting on the network control the network and decides who is rich and who is not; and whether the miners get paid or not.
If literally 100% of miners switched, leaving zero on the original chain, then people will have no choice since it won’t do any more transactions.
But if, say, a mere 99% of miners switch, it’s far from a given that people would follow. Having more mining capacity makes the chain more secure, but it’s not that big of a deal.
And anyone can become a miner. It's not reasonable on small rigs because there are so many miners now, but if most of them leave, then the common man can get back in to mining.
There is an interesting failure mode, though. Bitcoin is supposed to adjust mining difficult every two weeks to maintain the pace of roughly one block every 10 minutes. But that interval is based on block count, not time. Adjustment happens every 2016 blocks.
If miners suddenly fled en masse, it’s possible for the chain to be left stranded where the small number of miners remaining couldn’t realistically get to the next 2016-block interval to adjust the difficulty down to match the drastically decreased mining capacity. If mining capacity dropped by a factor of 1000 and it happened right after an adjustment, then bitcoin would be producing about one block every week, and it would take about 40 years (if mining capacity stayed constant) to reach the next adjustment.
This is well known and studied. I’ve produced and field tested an alternative, close to optimal adjustment algorithm and the code for a soft-fork transition. This could enable a set of miners to get “pre-agreement” on transaction ordering in an out of band forward block chain while they work to fight down the difficulty of the old chain.
I don't know what the specific mechanism would be, but I would bet that it relates to the billions of dollars backing the current ecosystem, and the interests of the people behind them. If the right event or crisis comes along, then people could be compelled to switch over to something else.
I'm sure there's someone out there still mining blocks on that chain with the exploit from 2010, but that's not where the mining power is. If the right series of events occurs, the miners will switch.