I cover this at the end of the article. Hinting is generally just a transformation applied to the glyph outlines before rasterization; it doesn't affect the vector graphics renderer itself. Adding hinting would not cause problems for the algorithm. (I personally consider hinting obsolete, but I would rather not argue about it.)
I'm not sure what you mean by "subpixel rendering". If you mean subpixel positioning, that is correctly handled, though not fully exposed in the API yet. If you mean subpixel AA, that is straightforward to add, and I expect it to improve performance relative to the CPU rasterizers by effectively tripling the glyph area.
Watch out because some CJK fonts from Microsoft require hinting to render correctly. They are made up of composite glyphs where each sub-glyph corresponds to a brush stroke and hinting is used to scale and position them.
> (I personally consider hinting obsolete, but I would rather not argue about it.)
That depends heavily on your preferences in font rendering, and in particular whether you prefer Apple-style "accurate shapes with no respect for pixel alignment" or Windows-style "monitors have pixels, better to ignore the designer and snap to pixels than to be blurry" rendering.
It also depends on the fonts you use; some fonts don't need hinting to look good, while others do.
If you do add subpixel AA, please make it optional. Some people, like me, can directly see the colour artifacts from it, even on hi-DPI displays. And others have multiple displays with differing orientation or pixel layout.
Hinting is very much obsolete on modern systems. I haven't used hinting with my text in many, many years, and yet fonts are visually superior to a typical Windows PC with hinting enabled.
Hinting is not obsolete.