So, LiquidThreads. :)
If most of the discussion goes around tree structure discussions, and how some advanced users find wikitext's free form to be an advantage, maybe we can agree on certain points based on where exactly is LiquidThreads being used.
* User talk pages. Do we need multithread tree discussions in our user talk pages? No, we don't.
* Regular talk pages. In most cases a section gets 2-5 replies at most. The benefit of a simple entry point for newcomers and junior editors clearly surpasses the potential inconvenience for some vets, especially if our priority is to be welcoming and open to diversity of people and opinions.
* Forums open to new / junior editors like https://www.mediawiki.org/wiki/Project:Support_desk . If you notice the number of replies per thread, you will see that almost always they keep themselves under 10 posts, so I don't envision major problems if we move those to Flow as well.
* Hardcore forums for insiders. I wonder if there is any using LQT nowadays, the ones that come to mind are based on pure Wikitext, and in fact they are not even in a *Talk namespace. Therefore, even if Flow would be powering 100% of the talk pages in Wikimedia wikis, it would be still a decision of these forums to decide whether they want to stay with Wikitext or use Flow.