Do you not see how cluttered this will make forums? Maybe the search engines will love it, but regular forum users (humans) will have to wade through a sea of threads. It's just plain nuts.

Can you at least try to think of a way to just display only the parent thread for human users, that loads the individual pages, and let the google bots gorge themselves on the countless component parts? Say when a Google user clicks on a search result called 123-Some-Topic-Part-10.php, when the user gets see more to your site, they will load 123-Some-Topic.php with Part-10 dynamically loaded into it. Is this remotely possible?