Simon and I had a discussion with James Ramsey, a project manager with
GitLab, around Simon's document a few months ago. They identified their
first priority as work on merge queue infrastructure (another request of
ours, although it's not on Simon's list); this work is tracked as
gitlab-ee#9186 and a version of it will be shipped in GitLab 12.0, next
month's release.
James made it clear that another of his priorities for this year was to
look at the current discussion interface and try to mitigate the sorts
of problems that we are encountering. Simon proposed that the situation
could be improved by presenting comments chronologically. James found
this to be an interesting suggestion and said he would add it to his
bucket of ideas.
With respect to timing: There were understandably no concrete timelines
given. James said that work on the discussion model would likely only
happen in the second half of the year (which we are now just entering).
Since then work on the merge train infrastructure has progressed a bit
more slower than expected, so I suspect things may happen a bit later
than expected. Moreover, neither gitlab-org&855 nor gitlab-ce#56481 have
milestones yet so I expect the timescale is at least on the order of
several months, unfortunately.