Support for Menu Block module?

There's the Menu Block module with over 100'000 active installs.

I would like to wrap blocks generated by it with the <nav> tag.

I dunno which of the modules needs extra functionality for them to work together. Please have a look. If it's Menu Block to provide extra functionality to leverage Borealis Semantic Blocks, could you please at least provide some guidelines for them? I'd be happy to post a feature request for Menu Block and paste your guidelines. Or whichever way you suggest.