We're not in a hurry to try and move people off Slack or GnuPG: teams have their existing services (Slack, G-suite) and other workflows like Thunderbird + Enigmail, git signing etc. We think complementing those existing flows is the way to go.
The longer term vision is that your team can sign up to Fluidkeys, download it and it sets up everyone's email client, git, pass etc according to your team's configuration. Then it quietly keeps everyone's keys updated when people join and leave the team. (and we rotate encryption subkeys every month)
Back to today: 0.3's sending secrets feature is a small diversion from that goal, but we hope a useful feature in its own right :)
I'd love your feedback on the vision above!