I’m not aware of any theme components that do this at this point. The problem isn’t so much about parsing the markdown; that’s not that difficult.
The problem is that it can get noisy and distracting very quickly. You’ll also have to parse the title in all the different places where it’s used. Otherwise, it looks good on the topic list, and you get this in notifications
You’ll also need to spend some time on the styles.
Like Sam mentioned, this is doable in a theme component. It will probably be an 8-10 hour job if you want to create a topic for that in the Marketplace category and see if you get any offers from our community developers.