Billion Kelvin operating temperatures make me super skeptical about the practicality of that solution in my lifetime. It's just so many orders of magnitude beyond where our materials science is.
The current design for ITER, operating at 150 million Kelvin, focuses the exhaust plasma onto a dedicated divertor surface with an estimated peak heat flux of 20 MW/m2. Experiments show that tungsten handles this fairly well, although with some cracks appearing after many cycles, but this is an active area of research.