OK, I see what you want. In fact the post would be splitted into several pieces, those enclosed into the tags, say [newhtml]...[/newhtml], and that need no markup treatment -if HTML is On- and the rest that needs a markup conversion.
That would be a very nice and powerful feature, indeed. It would solve a lot of troubles we have now because of the mix of HTML and MARKUP.
Only Scream can do it. I mean this feature needs to modify several scripts and to find a simple way to keep backward compatibility.
Scream, what do you think about this feature request? I think it's worthy to seriously consider it.