There aren't any plans at the moment. We've struggled with this problem before, and wrote something similar with https://github.com/khan/KAS/ but we've never worked at doing something inline. We use MathQuill in a couple places, which does the input decently (writing works, but typing something like x^2_2 gives you x^{2_2} not x^2_2), but the output doesn't look great. It's hard to do what the user wants, have clickable bits, and still have good looking output.

I recently made this little tool for writing latex macros: http://kasperpeulen.github.io/PressAndHold/ It works the same as the OSX press and hold accent picker. I have also a unicode version which I think is much more appealing for young mathematicians: http://kasperpeulen.github.io/PressAndHold/Unicode/

All MIT licensed if you are interested in using it.

I agree that it's a very difficult problem. I think that it's a major missing piece for online math learning right now (actually interacting with math symbols in a non ASCII/textbox way). Thanks for all of the hard work you guys do!

Desmos (supporting MathQuill) is leading the space here I think: https://www.desmos.com/calculator

Absolutely agree that if this was made and made open there would be a lot of opportunities in the math education space.