Possibly. It’s possible the Q70 will disappear entirely if/when Infiniti finally decides to make an all-electric flagship. The current gen Civic has been around for several yrs, and there’s been no word at all about an ILX replacement. I haven’t heard any rumors about a Charger/300C replacement. Rumor is that the Lexus IS/GS will not be replaced (at least in the US). If they are replaced, perhaps it will be a joint platform w/ Mazda.
Those sedans have been around so long that the tooling costs have presumably been recovered. Why not just con’t to produce them until the can’t be modified to include the latest safety/electronic equipment? At that point, I think we will indeed see some sedans disappear.
Mainstream family sedans (CamCord, Sonata) will probably never disappear, and, as you’ve mentioned, seem to be getting much better in some ways.