So now Cubase Pro 12 is installed

How are we going to be able to run all our Steinberg licenses on 2 pcs or is this a work in progress?

It is a work in progress.

Cubase Pro 12 works for me on two PCs. The Dongle is necessary only for older Cubase versions or other programs/vsts not in the Cubase 12 installer.

It does here too. However unless all your other eLicenser plugins work on 2 pcs it’s not a lot of use! I’m guessing it will be used as a vehicle to get people to upgrade to the new software versions as and when they become available.