I have re-submitted this request in the Cubase 9 Requests forum here: Option to Hear Overlapping Lanes - #2 by joegab - Cubase - Steinberg Forums
Please check it out and vote it up.
Note that I have asked for “the option” to hear overlapping clips so as not to break Cubase for anyone that prefers the current functionality. Hopefully, this will make everyone happy and preclude any dissent.
Thank you!