Ethereum's hard fork Istanbul may be postponed due to Parity developers delays

The scheduled Ethereum hard fork Istanbul can be postponed as Parity's developer team is not ready to deploy critical upgrades to the test network Ropsten on time. 
Istanbul shall be activated on the test network before the update is launched on the mainnet. 

However, Parity's developer Wei Tang believes that the team needs more time to fulfill the tasks.

“We need time till September 6 to finish the implementation. Not only because we accepted EIPs late but right now we just happened to be a large code base refactoring and we probably want to merge them first before merging Istanbul EIP,” he explained.

A testnet block number was supposed to be picked on the last Friday call, on August 23. However, it did not happen due to Parity. The team needs to finish their work before a testnet number is picked. 

The mainnet hardfork was scheduled for October 4th, just before before the Devcon5 conference in Osaka, but now it might be postponed until November depending on Parity's progress and testnet deployment results.

Currently, about 21% of nodes within the Ethereum network use Parity client. Geth is supposed to be the most popular client as it is used by 76% of nodes. Notably, Geth developers have already implemented all the required updates.

Earlier in August Ethereum developers approved the final details of the upcoming Istanbul hard fork. It will be activated in two steps. The first step was supposed to happen in October and include all six updates (EIPs).

The second step will take place in the first quarter of 2020. It will include changes that still require more work and testing, like new ProgPoW mining algorithm.