Fair concern, and fair question.

In order. I'm curious as to whether your concerns with Disqus are offset at all by it never being user-facing? At the moment I'm looking at it as a convenient and relatively robust back-end. Because the accessibility stuff is a big problem. That doesn't really solve all the concerns with using them, but I want something that does what DW doesn't (currently) do is handle synchronization of threads, which is something that Disqus handles explicitly.

As for the second question, there's always the faint glimmer of hope, but that's not the main reason. The main reason is that there end up being a number of useful (I think, anyway) uses purely within a single DW instance. For instance, if you cross-post something to multiple communities, you can share threads between all of them. This isn't, of course, always desirable behavior, but sometimes it would be. Additionally, it will allow for this sort of connection across potential future instances of DW (the software).

I don't know if that's a good response, but that's what's in my head, at least.