The economic "problem" is that ultimately fusion is a heat source that turns water into steam which turns a steam turbine. Solar and wind are approaching the cost of just the steam turbine alone. There is hardly any room for fuel and operational costs.

Even today steam turbine plants produce higher cost electricity that natural gas combined cycle plants.

The only difference between existing superconductors used for tokamaks and a RT version would be the energy cost of cooling the magnets to keep them below the critical temperature. Cooling does take a significant amount of energy, but I don't think that just getting rid of that would mean fusion produces enough energy compared to the cost of building the plant to compensate.

And of course, a room temperature superconductor can have better or worse qualities than existing conductors in other ways. If it were much heavier, or required more expensive raw materials, or had lower critical current, it could in favt be worse than the existing solutions (the extra construction costs could offset the extra energy output).