My bet is that we will see Lr7 at the same time as LR CC 2017.
Presumably LR7 will be LR CC 2017, so yes one would expect them at the same time!
At the same time, I don't get the point of "CC 2017" vs "CC 2015". I thought there was only supposed to be "One CC". The need for a "CC 2017" must be due to to something that the smart boys at Adobe understand better than I.
When they launched CC, that was a big selling point: only one future version, and you always get the latest version with your subscription. However, marketing guys like new releases that they can shout about, so from time to time they give it a slightly new look and feel, and change the launch splash screen image, and give it a new name. Otherwise people ignore the incremental changes, and say "Oh, you haven't changed it since 2013 when you launched CC."