Static publishing of dynamic content (e.g., publishing SSI or PHP files) could make inlining of comments from another system fairly easy. My only worry would be that the result would have all the complexities of both a fully dynamic and fully static system. I think the general architecture -- splitting posting from commenting, among other possible splits (e.g., splitting feeds into one product and tags into another) -- has real merit. I just don't want to experiment at the moment ;)
But that's all the more reason to have an escape plan for this next blog software as well.
What do you think about static publishing of an entry that uses AJAX to grab dynamic comments? Sure, it's two calls back to the server, instead of one, but at least one of those calls (and perhaps both, if the software was written cleverly) could be served directly from apache, no Python needed...
Just a thought.