Turns out we are currently working on that right now! We did a test conversion of VE/Feedback yesterday, and found one issue that needs to get fixed. ErikB is fixing that, and we'll do another couple test conversions for active pages on Mediawiki. Once that's done, we'll be able to convert everything on Mediawiki over to Flow.
So: coming soon -- probably next sprint. Hooray!
I sent out links to a particular (new) thread on that page yesterday. I request that we not confuse dozens of users or break any links by converting that page for at least another ~10 days.
In terms of LQT to flow conversion we edit the old pages into redirects. Any direct thread links should still work. That said I have found some other issues with older content in MW.org fixing merging and deploying will take those 10 days