Quote from: streetlight on January 28, 2018, 03:40:51 PM

As far I know a fork does not have any impact on the orginal blockchain.

That depends on what kind of fork it is. For example, a soft fork that occurs without majority miner enforcement can cause a wipeout attack on the original chain. Replay protection is not possible in soft forks, nor would it be required. So, this can happen in a UASF:

1) UASF occurs with very little hash support.
2) The majority of transaction volume moves to the UASF fork, even though its the minority fork.
3) Miners, driven by profit motive, switch to the UASF fork.
4) Eventually, the UASF chain gets more cumulative work than the legacy chain. This causes a chain reorganization that wipes out all transactions on the legacy chain going back to the fork block.

That means that anyone who received a payment between the UASF block and the reorg will lose that money. Given the time involved, its possible that thousands of confirmations could be undone. This is an extreme scenario, but its good to be aware of.