Why do RTSC mean fusion? We already have LTSC that can be used in tocomacs. From your charts, the RTSC falls apart above 100C, so it would still need to be cooled in applications like fusion.
Discussion
HTS magnets like REBCO still require cryogenics and still heat up due to plasma pressure.
Most of the fusion experiments to date are limited in duration and power by overheating magnets.
RTSC removes both the heating and the cryogenics. Is a massive advance for fusion.
Pretty much leaves neutron damage as the final barrier.