The really big remaining question in Scripting2 is how to use hierarchy. 

Sub-text just scratches the surface. I can include as much hierarchy as I want in these posts. The question is how does that get represented at read-time? 

Also, since every post includes a link to the OPML source code, it's easy for other people to experiment. Just read the HTML, find the link to the OPML and render it any way you think it makes sense.  

I'm going to be thinking about that a lot in the coming days.