They have a reason for the delay, and that is to perfect the system before the launch, they know very well that their competitors are taking this opportunity to launch their own chain or bridge their chain we are all going to benefit if they launch their system in the right time, any way we have a good alternative in Binance Smart Chain.
It's going to be a good competition and will enhance users' experience once they launch so we have to be patient and wait.
Ethereum is big platform and if you look beyond cryptocurrency, big corporations like Google have challenges to any internal reconstruction for strategies, staffs, ... Sundar Pichai is very carefully and slowly to make important decisions of appointments for Google.
Vitalik and Ethereum team have to been as most carefully as possible for the upgrade because any fault will be terrible. They don't want another DAO hack. Ethereum nowadays are the second giant in cryptocurrency industry and they don't want to lose it just because an upgrade.