Thank you for raising this in the forums. During our planning period, we started to scope out the various changes required within the forums and the amount of work required for each.
Unfortunately when we looked at both ForumNG (mod_forumng), and Advanced forums (mod_hsuforum), we felt that they were not quite the right fit for Moodle. This was in part because we felt that some of the features included in these solutions did not fit outside of the specific requirements for which they were written for.
As an example, both solutions include an anonymity feature, but implement them differently. mod_forumng only allows tutors to post anonymously, whilst mod_hsuforum only allows all users to post under the name 'Anonymous'. Both were written for the HE market, but clearly there are major differences in the perceived requirements. Neither of these implementations allowed for use-cases such as role-playing which are an important pedagogical tool.
In any case, if we had decided to migrate to either mod_forumng, or mod_hsuforum, we would have needed to either rewrite within the existing mod_forum plugin, or to provide an upgrade path from mod_forum to the chosen module. In migrating from mod_assignment to mod_assign we learnt many lessons about renaming modules and refactors of this kind... although this was largely a successful migration, it took us many releases to get things into the right state to be able to finally remove the old module.
Instead, we have opted to look at each feature in turn and look to improve the existing forum to add the desired functionality. The aim is to improve the forum for the largest number of users and support as many pedagogical approaches as possible.
The encompassing issue for all of the forum changes that we've been looking at is MDL-39707. MDL-1626 is one of the components of this overarching issue and is one of the most requested features of all time within Moodle. I'm hoping that the feature will be integrated this afternoon and will be rolled in weeklies on Thursday. The next forum-related task we aim to look at is likely to be the layout and UI refactor (MDL-41773) with the key aims of this task being to make the user interface more accessible, and clearer. It's likely that this will incorporate a couple of the other issues (e.g. MDL-8501, and MDL-33692). I can't give a timescale on these, but the intention is to have these in place for the Moodle 2.8 release.
With regards the roadmap, Martin updated the roadmap recently to give more consistency and to list each project that we are working on.
Hope that this helps,