If not grafted or still alive above the graft may be able to come back. But cold winters will be able to come back also.

It's grafted. :( The trunk below the graft (around 3' tall) has bark lifting all the way around and the next layer (phloem?) is black.

A large portion of the upper graft is still green. How does it live without the lower main trunk?

It just is taking awhile to die is all.

So you think the winter got it? I have a regular controversa which took my -10 zone 6 winter just fine

Yes, I think it was the winter. We had 12 days of subzero temps straight...in the negative double digits...plus overall the coldest Winter since who knows when....windchills of -50 etc. The tree is around 10 years old and has been pristine...don't know what else it would have been.

Really stinks!!!!