Summary, the Ubuntu team plans to remove the synaptic driver on upgrades since it confuses GNOME, that might have an impact on Unity users though since unity-control-center doesn’t know how to configure libinput
You can read the details on
The plan is to have the dist-upgrader removing xserver-xorg-input-synaptics and not use Conflicts, that way users who need it can install the old driver back (that could include Unity users, though at the cost of creating issue for GNOME sessions) and nobody is going to uninstall GNOME by mistake.
Ideally the Unity team would update unity-control-center to be able to configure libinput (the topic might be on topic for the Unity subsection of the forum but it seems one needs special permissions to post there).
Next cycle we are probably going to look at removing xserver-xorg-input-synaptics from the archive since libinput should be then good enough for everyone by the next LTS and the recommended solution.