For the past year, people have been predicting an iPad Pro, but Apple has not delivered. Here were the expectations of it....
iPad Pro
12" Screen
Running full OS X
Ultra Portable
Retina Screen
Keyboard compatibility similar to Surface tablets
Meant as a more compelling iPad for productivity
Single Port
Slightly more powerful processor
Fanless design
Here is what rMB delivers
12" Screen
Running full OS X
Ultra Portable
Retina Screen
Keyboard
Non Touch-Screen
Single Port
Slightly more powerful processor but basically same level as iPad Air 2
Fanless design
So literally the only difference between the rMB and the expected iPad Pro is that the rMB doesn't have touch screen, but does have a keyboard.
Performance wise, the rMB performs as if you were to take the processor out of the iPad Air 2 and put it in a laptop.
It isn't likely that Apple is going to release a 12" iPad Pro now that the rMB has filled that niche. The rMB is likely the 12" device that rumors have been mentioning.
iPad Pro
12" Screen
Running full OS X
Ultra Portable
Retina Screen
Keyboard compatibility similar to Surface tablets
Meant as a more compelling iPad for productivity
Single Port
Slightly more powerful processor
Fanless design
Here is what rMB delivers
12" Screen
Running full OS X
Ultra Portable
Retina Screen
Keyboard
Non Touch-Screen
Single Port
Slightly more powerful processor but basically same level as iPad Air 2
Fanless design
So literally the only difference between the rMB and the expected iPad Pro is that the rMB doesn't have touch screen, but does have a keyboard.
Performance wise, the rMB performs as if you were to take the processor out of the iPad Air 2 and put it in a laptop.
It isn't likely that Apple is going to release a 12" iPad Pro now that the rMB has filled that niche. The rMB is likely the 12" device that rumors have been mentioning.