Well, I hope that the team member will get better and since the release of the merge was already close, even if there's only slow progress it should be done very soon, assuming what was told in the updates was true.
This is one of the projects where I would love to be part of the dev team, just to see the site of the problem and fix it. If a team member gets sick that's bad, but for a project there should be ways to still continue, especially if it's that long. I've read the comments on the reasons, but they should not happen.
Next merge, they should work on the merge in a separate branch while they continue to work on the new content and release it in the old system. Might lead to a bit more work overall, but it doesn't stop the work all together. The Week 1 merge took months longer than expected and with Month 1 it's now almost a year. Can't imagine what could happen with the Month 6 merge.
But I'd love to see what work was done for the merge. I can't explain why it took so long (even if the team member working on it wouldn't hae gotten sick). Even if the old code base was crappy, there's nothing that outstanding in the game that I can see cause that much work when refactoring everything.