It looks like some people in the thread below have figured it out — we actually have this. You can start a chat both ways; the system will automatically recognize if this person is on Skype for Business or on Teams.
Thanks and let me know if you have any questions.
An error occurred while saving the commentMatt Wood commented
If it's tagged as "we have this!" does that mean it's now being ignored? MS Teams definitely does NOT have proper two-way interoperability. A Teams user cannot initiate a chat with a Skype for business user, making transitioning from SfB to Teams much harder.
We are working on the release of the Tasks application in Microsoft Teams that will aggregate data from Microsoft To-Do, Planner and Outlook with more capabilities on the way. You can see Planner data in Kanban views today, and the Tasks app will continue to support that view. In January we announced task publishing which will release with the new app. Get an overview at https://youtu.be/rTATVGroEsQ.