This is so powerful, it makes me wonder why they didn't just make a new markdowny syntax for Latex so they could reuse everything from the Latex ecosystem. A bit like what CoffeeScript was for JavaScript, I mean.
You'll likely lose a lot of the ecosystem since a lot of stuff wouldn't expect such a syntax.
That assumes that the only issue with LaTeX is its syntax. Other issues I can think of are that LaTeX doesn't generate HTML and that LaTeX is completely Unicode-disabled.