It's not technically available unless you are comfortable doing some wildly fun hacks. More options supposed to be coming with Aurora though.
With that said, let's go crazy. You can put multiple templates inside a single Email template. In this case, let's use badges. Most communities have a single badge template that is sent out for all badges. We have about a dozen at this point, with more coming. If user A completes learning path A, they will receive badge A. As such, we have an entire code snippet within the badge email template as it relates to badge A. OR, User completes learning path B. OR, User completes learning path C. Each of these has an entirely different email that goes out with different information on next steps for the user to take.
If you want to send out an email anytime you want - Just create a fake 'badge', customize the email, award a custom attribute to the users you want to get said email/badge, and away you go (Hide badge from their badge page).
You can do similar things with the rank emails, or using roles in a variety of ways probably, etc.
TLDR; Break stuff to make it work.
