[mrbiber]

Riot.im is almost there, together with e2e crypto, foss stack, server federation and bridges to slack, irc etc.

[mixedCase]

Riot is a good alternative to IRC, Slack and other team/community chat systems.

It's not an option for the international 1 on 1 most Skype users are used to. The closest option seems to be Wire, but I've yet to try it.