It's interesting that there seem to be so many SKUs here, and both with and without HBM.
So, assuming there are some cards with HBM and some with, two possibilities exist:
1. There is one piece of Silicon, with ability to support HBM *or* GDDR5. This implies there are two memory controllers, especially given how different the two techs are - one is 4096bit with a low clock rate, one say 512bit with a high clock rate. Seems like there would be quite a chunk of wasted silicon, which, given that Titan X/GM200 is on the limits of the 28nm process and is "all graphics" implies it would be a bit slower than you would hope.
2. There are two different dies here. This would also shock me, as if AMD had a GDDR5 version you'd think it would be ready sooner (not as revolutionary as HBM) and you'd think they would have pushed it out the door to counter 980/Titan X.
I do wonder if we will end up with 390/390x with HBM on new dies, then 380x being rebrands of 290x.