if a clone is plugged in what does it say?
the same thing is says now, and has said since Arduino first appeared?
Actually, I predict that the cloners will clone the Arduino USB vendor ID as well; the USB community hasn't been all that aggressive or capable when it comes to policing "illegal" activity. (you know those multi-cable sets with little adapters so you can use the same cable for A host, A device, B mini, B micro, AND MORE!? NOT "allowed"!)
It would be nice to see some official "direction" about what the more careful derivative vendors that choose to implement the new hardware are SUPPOSED to do; it was a nice feature of the FTDI chips that FTDI let people ride on their vendor ids...
I believe that it is technically feasible to configure an FTDI based arduino to include the Arduino USB vendor id. This is/was another feature of the FTDI (you would still need the FTDI drivers rather than the built-in windows drivers.)