You can clearly see an initial steep spike to the curve where mobile adoption was new and fierce, and then the curve starts slowly becoming less steep over the last 10 years. It will peter out and remain steady when mobile device adoption reaches critical mass.
No, as I pointed out in another reply to you, home internet is commonly dual-stack (at least in the US and many other countries), and machines with dual-stack connectivity can and do use IPv6 to connect to sites that support it. You can verify this yourself using Wireshark or similar tools.