@Bitcoin Cash integration was a simple fork of the existing @Bitcoin chain. Trezor promised to develop BCH integration in its wallet, only to find out that it is not so simple.
The hard fork of Bitcoin to create Bitcoin Cash on Aug. 1 resolved in a difficult question for Bitcoin service providers, including wallets and exchanges - Should they support @Bitcoin Cash integration?
Multiple service providers decided they would not and asked users to withdraw their Bitcoins or transfer their Bitcoins to other wallets, if they wanted to get Bitcoin Cash on Aug. 1.
Given that Bitcoin Cash was only a split of Bitcoin's Blockchain, and that Bitcoin Cash had replay protection in place, Trezor announced that it would support BCH integration.
Users who wanted to access their Bitcoin Cash would have been able to do it through a simple interface, accessible from the Trezor wallet. Users were given a guide to claim their Bitcoin Cash from their Trezor wallets.
Problems faced
The support for BCH was developed in a week's time and Trezor developers have acknowledged that it was a painful and stressful week. The development of the firmware for BCH integration, with the documented changes, went smoothly.
However, the deployment of the BCH implementation of Bitcore (which is a backend for all cryptocurrencies supported by the Trezor wallet) caused several problems.
Bitcoin ABC, which is a full node implementation of the BCH standard, had made several changes to the code, including style changes. That made comparing code and implementing Trezor support a time-consuming task.
A particular bug caused transactions to disappear and negative balances in wallet addresses, necessitating code rewriting and taking the backend offline.
Universal wallet - a utopian dream
The increasing number of 
Often, there is fear of malware masquerading as a wallet being installed on a computer. People avoid this by storing their minor 
However, this strategy poses users to the risk of the 
As the difficulties in Bitcoin Cash integration have shown, a universal wallet (hardware or software) capable of storing all cryptocurrency remains a utopian dream.