We're redesigning our application's plugin interface, so we're using the Adapter pattern with our proof-of-concept design to show that the new interface will function without committing to using it in the application itself.
We don't know what to call this new interface. It serves the same purpose as the old one - let's call that one
CAbstractAppPlugin. Furthermore it will likely be, like its predecessor, an abstract class rather than a pure virtual interface (C++) indicating that we should still use "CAbstract" instead of "I". Slapping a "New" or "2" onto the name seems silly, but adopting a very similar name could lead to confusion until the old one is deprecated.
So how do you name a thing X that's replacing thing Y?