At the end of July we told you that BMW was planning a slew of model cuts in an effort to save some cash. The first of those cuts has just arrived, for 2020, there will be no 3-Series GT, 6-Series GT, or 6-Series Gran Coupe. This announcement effectively kills the 6-series lineup entirely which the 8-series has taken over for. The GT versions of the 3 and 6-Series never caught on and visually looked ungainly.
That enough would be perfectly good enough reason for canceling the cars, but the real reason has to do with the markets massive shift towards SUVs. Already the X3 is outselling the entire 3-series lineup on a regular basis, so keeping such a low volume variant around is probably not in the best interest of a company wishing to cut costs. We'll update you as we find out about more cuts to the BMW line.