While it's possible to build a lot of things on top, maybe it'd be worth making some minor updates to the core TeX engine itself, to bring it into the world of

While it's possible to build a lot of things on top, maybe it'd be worth making some minor updates to the core TeX engine itself, to bring it into the world of Unicode and OpenType fonts... Oh, there are a couple of such candidates, actually, built with very different philosophies: there's XeTeX, intended to graft Unicode and OpenType support onto TeX with as little disruption as possible, such that it "just works" with minimal effort; and there's LuaTeX, which "deconstructs" TeX to give you an infinitely-flexible typesetting toolkit that can do just about anything, if you can figure out how to wield it.