From Autonews.com...puts the future of the 6-series into perspective (and what I've been saying for a while)
What will BMW do with the 6-series cars? Believe it or not, the big coupe and convertible are going to get bigger. The new big coupe will be badged as an 8-series, which was originally offered from 1989 to 1999, to go up against the large Mercedes yachts.
A large two-door coupe (8-series) is expected to land in 2018 and will be positioned between the current 7-series and the Rolls-Royce Wraith in the greater BMW universe. An 8-series convertible will follow later in 2018, suggesting that the 6-series convertible is also living on borrowed time. M8 versions of both land yachts are expected, as are 12-cylinder versions.
This leaves the 6-series Gran Coupe with nowhere to go, though the 6-series range itself could live on if the next 5-series GT is renamed the 6-series GT (which has now happened). This will, at the very least, keep the range fairly well spaced out in terms of size, even if the 6 series you remember from the 1980s will have nothing in common with the offerings in the 6-series lineup. But we're used to abrupt changes in the BMW naming scheme by now.