Sell our own bitcoins on core chain;
After the switching from core chain to XT chain accomplished, the previous bitcoins are still available, can we proceed the operations?
Yes, you just need to "taint" your bitcoin with newly generated bitcoin. After the first >1MB block is generated,
1. Ask someone to send you some bitcoin (1 satoshi is enough) which is generated on the new chain after the fork (or taint bitcoin created with this method)
2. Using an upgraded client (e.g. Bitcoin XT), create a new address and send all your bitcoin to yourself . Most importantly, the transaction input has to include the bitcoin from step 1. Wait for several confirmations.
3. Now you have 2 independent sets of bitcoin. You can safely send your old bitcoin to other people using an old client, e.g. Bitcoin Core 0.11.
Note:
a. It is very important to make sure the bitcoin from step 1 is truly taint bitcoin. Use a block explorer to follow the history of the coin, to make sure at least one of its ancestors is a coinbase transaction AFTER the first >1MB block is generated. A merely activation of BIP101 (i.e. 750 out of 1000 blocks support) is not enough. The fork does not happen until the first >1MB block is generated
b. If you send your old/new bitcoin to someone before step 2 is done, you are at the same sending your new/old bitcoin to that person.
c. If the fork is really successful, it is unlikely that you will be able to spend your old bitcoin, because no miner will be mining the chain. Even if a few miners are running, the small block size won't be able to handle your transaction.
This is almost suicide
Suppose that 75% of hashing power has switched to XT, and rest 25% stays at core. Is it possible that now XT becomes the main bitcoin chain and everyone moved to that chain following the fork? Far from it
Bitcoin is a whole global financial system, it is not only the blockchain, but everything that builds upon it. There are many exchanges and payment processors, merchants, security service provider and investment funds etc... and you must persuade all these participants to accept the new chain. And I guess many of them are experienced financers which always take conservative approach when it comes to change
Because pre-fork coins can be spent on both chains, if some of them (especially those with large amount of bitcoin holdings, and typically the core supporter of bitcoin) do not like the idea of XT chain, they will dump their coins on the XT exchange, so that any exchanges trades the XT coin will have a near-zero exchange rate when they are facing millions of coins dumped after the fork. And when XT coin worth nothing on exchanges, the whole hash power on XT chain would be a 100% loss, those hash power will switch to core chain, thus core chain regain the hash power and become the longest. In one word, if there is a conflict of interest, it is who have the most bitcoin decide where bitcoin is going, not who have the most hash power
Of course the XT fans can also dump their coins on the core chain, then value on core chain will also be heavily cut, but I guess the core chain would still have less sell pressure due to XT fans have less coins. Anyway this kind of mutual destruction will hurt the ecosystem significantly while achieving nothing
There is always unknown risk on XT coin: Core coin has hold its value very well for several years, but no one knows if XT coin would achieve the same thing, it is not time-tested. So XT coin faces a dilemma: without being time-tested in real economy, it can't gain value and go mainstream, but if it does not go mainstream, it will not get any test... This dilemma will make the fork of bitcoin extremely unlikely. Only a small change, with over 95% consensus throughout the industry would work
Should be enough for another couple of years
