I can’t speak to the superconducting potions of this comment, but the general computing information is mostly correct.

Switching losses are a result of capacitance in the circuit. These capacitances aren’t going anywhere in transistors made from semiconductors. Additionally, even when a transistor is on it has some resistance, which of course creates heat whenever a current moves through that transistor. Leakage current also generates waste heat.

I could see room temperature super conductors being useful as replacements for bus lines in a digital circuit, but this wouldn’t eliminate the heat in the circuit. Most of the heat is created in the transistor junctions, so the effect would be very minimal if even noticeable.