A few, but none with enough momentum to win over the mainstream. See Tox, Vector/Matrix, Jitsi with OTR... Otherwise there are web-based solutions that work well. Is it talky.io?
EDIT: Not forgetting Signal, of course. But I think you mean video comms?
I'm cautiously impressed by Matrix's momentum, to be honest (although I'm biased given I work on it) - we've got over 300K users on the matrix.org server now and around 1000 other servers visible from matrix.org. Meanwhile Riot.im (the app previously known as Vector.im) is hopefully pretty mainstream friendly...
I'm looking forward to Matrix too. It's still very immature right now through, as (as I understand it) we're still waiting for E2E encryption on mobile and group video calling(?).
It's hard to see Matrix as a standard right now too, with only one server and one client even remotely complete. Would love to see a multiplatform native client!
Thanks for the work you do, I realllllly hope matrix attains some success.
You can safely remove peer-to-peer from your requirements for an alternative.
If you are looking for an desktop app accessible to mainstream users, you can try viber.