There are technical reasons why this will not happen any time soon I have been told.
I agree it is really annoying and the reason many will not use this excellent app.
Honestly, in my opinion, threaded view is overrated, what happens when someone changes the subject, or when someone uses a client that does not support keeping the breadcrumb, you get two threads.
In my opinion Search or Filter by Subject/Sender/Receiver is a lot more important than threaded view.
Most other email clients have Search from Sender function while reading an e-mail. Sadly you cannot specify where to search for, or simply tap on an e-mail and have certain fields searched automatically. This is a bigger and more important feature that is missing, among a few others that would make AM a complete email app that can stand out from the crowd.
I like threaded views, but on a tablet or phone using IMAP you need to be careful what you wish for, as you may have limited storage, a limited data plan from your provider, and despite the 'instant on' nature of phones, and all the big numbers in the spec sheets, they just don't match PCs for number crunching or text processing speed. I really don't know how much of the task can be done entirely on the server, but I suspect any client designer has to assume the server is relatively dumb. I also think Android forbids any app grabbing more than so much memory (on mine it is 2gig).
If everyone in the conversation has a system that uses in-reply-to, then i think even changing the subject won't break the thread, and I find this is the case with emails from my friends - all of us by coincidence (also) using Thunderbird on various PCs, as well as some tablets and phones, but only I am using AM. so that need not be a problem.
However back to the IMAP issues. A threaded conversation stretching over days, even months, involves referring to emails that are by now only on the server. Performance and data transmission quota issues might arise, as navigating the thread involves going back to the server. Keeping emails on the tablet or phone just because they could be in a thread seems either daft or impossible, as any reply has an in-reply-to.
What I do miss is:
Search, filter or sort by sender, subject, possibly date, and ideally combinations, but I think in Thunderbird you can filter by one or more factor, then sort by another, so it is easy to make up for lack of threaded view (old versions did not have threaded, and I don't use it be default even now).
Like you, I miss being able to tap on the sender column and get emails sorted by sender, the selected one at the top (but again, this would soon be digging back into the server, with limited numbers 'live' on the phone.)
The other day I had to find a set of user credentials sent to me over 6 months ago. I had to turn to my PC, because I had less control over the search in AM, and for some reason, searches on the server return stuff sent 6 months ago right at the end, after everything else. Same broadly on PC as AM, so presumably a server thing**. However, AM did not return the wanted item at all unless I narrowed the search to get fewer hits - although it did return stuff that was nearby in time. Not sure if this is a bug or a feature :-)
So I would say, search by sender, subject, etc in a targeted way comes very comfortably above threaded in my wish list. Filter is also useful, as is sort by subject, sender, and so on. However, you then still are implicitly diving back into the server to find older items.
(** oddly, I thought I had Thunderbird set to download and keep locally 100% of all emails, so I will have to revisit those settings as the behaviour suggests it is still having to access the server, but that's my problem. I need at least one of my devices to survive loss of broadband! )
