Most next generation reactors already are high temperature.

All the major companies at the forefront of reactor commercialization have high temperature reactors.

The optimal today for a reactor is having one reactor with output X and then add 3X worth of turbines and a way to store hot solar salt. This way you can produce huge amount of energy at the times when prices are high.

Of course it also means the nuclear part of the project would only be a small part of the overall cost.