The answer to this has been posted on this ANN many times since 2016.

Ethereum is going to have a completely new system after POW finishes. No other crypto-currency will have anything similar in the sector.

This will mean issues like the volume of transactions and speed can be properly designed for.

Due to this, there is no copy and paste possibility and takes a lot of new coding and programming and a whole heap of extra testing before it can be fully implemented.