We have received reply from Electrum author. Plugin won't be included in wallet by default. Author believes it would create a law risk to add mixer into wallet. Our hook was merged so our plugin will work with new version, but it will need to be installed separately.

We have published an article at r/Bitcoin about how to use ChipMixer to avoid upcoming "declare cryptocurrencies" US law: https://www.reddit.com/r/Bitcoin/comments/6jzc41/easy_way_to_avoid_upcoming_us_declare_btc_law/