yeah i held out hope for a long time, but it has slowly faded away
just an FYI: the reason for the delay on the tmobile version was because of the bug identified beta testing of w10m (dealing with a 3rd party driver and ims registration. after several months microsoft engineers identified the problem and found a solution. the problem is that the fix needs to be done on a firmware level.
so back in january microsoft submitted the firmware fix to tmobile. all they needed to do was certify it and send it out OTA. well it seems tmobile didn't consider it worth the effort (minimal effort, since MS did all the work finding and fixing the problem)
edit to add:
another FYI some might find interesting
if tmo had pushed the firmware fix, then MS would officially push w10m. this is the reason tmo users need to go "insider" if they want w10m.
and as for my household (two tmo 640's) only one can run win10, the other has to stay on win8.1 since it used in a big office building during the day, and needs band 12 and all of the services that can run on LTE (ie. volte)