I don't think any insider will "confirm" anything let alone the radioactive TF figure.
If there is water to the whole 1.8GHz core clock for GPU holds any water for the final package, the worst case scenario with 36 CU active is just about 8.3 TF. If as previously mentioned, (presumably) GCN dev kit's (rumoured) 12.9TF were worth their salt then a RDNA card with a TF value of about 10.3 would not only do the same job, but exceed it due to other features like VRS.
So, with half a pint of salt- Worst case is ~8.3TF and personally ideal (because it breaks the 10TF mark making brochure worthy) is ~10.2 to 10.3 TF RDNA on a GPU featuring 44 to 48 CU active.
Now, how does this fit into the early rumours of 300mm2 die space... well others are better prepped with that knowledge.