I’d like it as a future requirement, to verify that the chosen database engine has a way to support it.
It might, even if it’s MS SQL database – e.g. store in some big XML field?
I’d like to think that it (and tree-like threaded comments) are reasonably foreseeable and that part of the MVP design (not implementation) includes its supporting future requirements and not only the immediate ones, i.e. to not “paint oneself into a corner”.
I wonder how comments are supported in the database anyway? If it’s SQL a naive implementation might put them in a separate table to be joined to topics, possibly instead they could all be denormalized in some XML field already within each topic instance?